Within the last few years, the early-summer emergence of vast waves of mayflies has caused great consternation among residents of riverside towns and motorists who cross the bridges over the lower Susquehanna. Fishermen and others who frequent the river are familiar with the phenomenon. Mayflies rise from their benthic environs where they live for a year or more as an aquatic larval stage (nymph) to take flight as a short-lived adult (imago), having just one night to complete the business of mating before perishing by the following afternoon.
In 2015, an emergence on a massive scale prompted the temporary closure of the mile-long Columbia-Wrightsville bridge while a blizzard-like flight of huge mayflies reduced visibility and caused road conditions to deteriorate to the point of causing accidents. The slimy smelly bodies of dead mayflies, probably millions of them, were removed like snow from the normally busy Lincoln Highway. Since then, to prevent attraction of the breeding insects, lights on the bridge have been shut down from about mid-June through mid-July to cover the ten to fourteen day peak of the flight period of Hexagenia bilineata, sometimes known as the Great Brown Drake, the species that swarms the bridge.
An adult (imago) male Great Brown Drake (Hexagenia bilineata) burrowing mayfly. Adult mayflies are also known as spinners.A sub-adult (based on the translucence of the wings) female burrowing mayfly (Hexagenia species). The sub-adult (subimago or dun) stage lasts less than a day. Normally within 18 hours of leaving the water and beginning flight, it will molt into an adult, ready to breed during its final night of life.
After so many years, why did the swarms of these mayflies suddenly produce the enormous concentrations seen on this particular bridge across the lower Susquehanna? Let’s have a look.
Following the 2015 flight, conservation organizations were quick to point out that the enormous numbers of mayflies were a positive thing—an indicator that the waters of the river were getting cleaner. Generally, assessments of aquatic invertebrate populations are considered to be among the more reliable gauges of stream health. But some caution is in order in this case.
Prior to the occurrence of large flights several years ago, Hexagenia bilineata was not well known among the species in the mayfly communities of the lower Susquehanna and its tributaries. The native range of the species includes the southeastern United States and the Mississippi River watershed. Along segments of the Mississippi, swarms such as occurred at Columbia-Wrightsville in 2015 are an annual event, sometimes showing up on local weather radar images. These flights have been determined to be heaviest along sections of the river with muddy bottoms—the favored habitat of the burrowing Hexagenia bilineata nymph. This preferred substrate can be found widely in the Susquehanna due to siltation, particularly behind dams, and is the exclusive bottom habitat in Lake Clarke just downstream of the Columbia-Wrightsville bridge.
Native mayflies in the Susquehanna and its tributaries generally favor clean water in cobble-bottomed streams. Hexagenia bilineata, on the other hand, appears to have colonized the river (presumably by air) and has found a niche in segments with accumulated silt, the benthic habitats too impaired to support the native taxa formerly found there. Large flights of burrowing mayflies do indicate that the substrate didn’t become severely polluted or eutrophic during the preceding year. And big flights tell us that the Susquehanna ecosystem is, at least in areas with silt bottoms, favorable for colonization by the Great Brown Drake. But large flights of Hexagenia bilineata mayflies don’t necessarily give us an indication of how well the Susquehanna ecosystem is supporting indigenous mayflies and other species of native aquatic life. Only sustained recoveries by populations of the actual native species can tell us that. So, it’s probably prudent to hold off on the celebrations. We’re a long way from cleaning up this river.
In the absence of man-made lighting, male Great Brown Drakes congregate over waterways lit often by moonlight alone. The males hover in position within a swarm, often downwind of an object in the water. As females begin flight and pass through the swarm, they are pursued by the males in the vicinity. The male response is apparently sight motivated—anything moving through their field of view in a straight line will trigger a pursuit. That’s why they’re so pesky, landing on your face whenever you approach them. Mating takes place as males rendezvous with airborne females. The female then drops to the water surface to deposit eggs and later die—if not eaten by a fish first. Males return to the swarm and may mate again and again. They die by the following afternoon. After hatching, the larvae (nymphs) burrow in the silt where they’ll grow for the coming year. Feathery gills allow them to absorb oxygen from water passing through the U-shaped refuge they’ve excavated.
Several factors increase the likelihood of large swarms of Great Brown Drakes at bridges. Location is, of course, a primary factor. Bridges spanning suitable habitat will, as a minimum, experience incidental occurrences of the flying forms of the mayflies that live in the waters below. Any extraordinarily large emergence will certainly envelop the bridge in mayflies. Lights, both fixed and those on motor vehicles, enhance the appearance of movement on a bridge deck, thus attracting hovering swarms of male Hexagenia bilineata and other species from a greater distance, leading to larger concentrations. Concrete walls along the road atop the bridge lure the males to try to hover in a position of refuge behind them, despite the vehicles that disturb the still air each time they pass. The walls also function as the ultimate visual attraction as headlamp beams and shadows cast by moving vehicles are projected onto them over the length of the bridge. Vast numbers of dead, dying, and maimed mayflies tend to accumulate along these walls for this reason.
The absence of illumination from fixed lighting on the deck of the bridge reduces the density of Great Brown Drake swarms. Some communities take mayfly countermeasures one step further. Along the Mississippi, some bridges are fitted with lights on the underside of the deck to attract the mayflies to the area directly over the water, concentrating the breeding mayflies and fishermen alike. The illumination below the bridge is intended to draw mayflies away from light created by headlamps on motor vehicles passing by on the otherwise dark deck above. Lights beneath the bridge also help prevent large numbers of mayflies from being drawn away from the water toward lights around businesses and homes in neighborhoods along the shoreline—where they can become a nuisance.
Lights out on the Columbia-Wrightsville bridge. Dousing the lights to eliminate fixed illumination on bridges is an effective method of reducing the density of Hexagenia bilineata swarms.With the bridge lights darkened, male Great Brown Drakes, their cellophane-like wings illuminated by headlamps to appear as white spots on the road, number in the hundreds instead of hundreds of thousands in swarms on the bridge near the east and west shorelines.Swarms of Great Brown Drake mayflies are still present at the Columbia-Wrightsville bridge, they’re just not concentrated there in enormous numbers. Evidence includes their bodies found in cobwebs along the entire length of the span.The aptly-named Bridge Orb Weaver (Larinioides sclopetarius) constructs webs along the entire length of the Columbia-Wrightsville bridge, and on many of the buildings at both ends. The abundance of victims tangled in silk must overwhelm their appetite, or maybe they actually consume only the smaller insects. They have their choice. Of the Bridge Orb Weaver, Uncle Ty Dyer says, “When you live along the river, it’s your friendly neighborhood spider, man.”The native Eastern Dobsonfly (Corydalus cornutus) is among the reliable indicators of stream quality in the Susquehanna at the Columbia-Wrightsville bridge. Winged adults, which live for about a week, are clumsy fliers attracted to lights. The aquatic larvae are known as hellgrammites, which require clean flowing water over rocky or pebbly substrate to thrive. Two adults were found on the bridge last evening. It would be encouraging to find more. Maybe we’ll stop back to have another look when the lights are back on.
SOURCES
Edsall, Thomas A. 2001. “Burrowing Mayflies (Hexagenia) as Indicators of Ecosystem Health.” Aquatic Ecosystem Health and Management. 43:283-292.
Fremling, Calvin R. 1960. Biology of a Large Mayfly, Hexagenia bilineata (Say), of the Upper Mississippi River. Research Bulletin 482. Agricultural and Home Economics Experiment Station, Iowa State University. Ames, Iowa.
McCafferty, W. P. 1994. “Distributional and Classificatory Supplement to the Burrowing Mayflies (Ephemeroptera: Ephimeroidea) of the United States.” Entomological News. 105:1-13.
It had been quite a few years, decades actually, since Uncle Tyler Dyer and I had visited the State Museum of Pennsylvania, formerly the William Penn Museum, in Harrisburg. Several days ago we decided to stop by to see what’s new.
I was fussing around with the official “Life in the Lower Susquehanna Watershed” camera while walking slowly down an entrance corridor when I heard Uncle Ty exclaim from up ahead, “Hey man, that’s my T-shirt!”
There it was, neatly screen-printed on luxurious , but functional, blended cotton and polyester, just like the one Uncle Ty wore forty years ago. This priceless gem was no iron-on job. It was the real thing, just like Coke, but a little bit more expensive.
A T.M.I. T-shirt just like the one Uncle Ty wore back in 1979 is among items on temporary display at the State Museum of Pennsylvania to mark the fortieth anniversary of the Unit-2 accident.
Uncle Ty said that, other than his own artistic creations, his T.M.I. T-shirt was the only one he wore during the summer of ’79. It even had spots of hardened wax in the fabric around the belly section where his candle had dripped during one of the anti-nuclear energy protest vigils he attended.
I wasn’t so certain, I thought he had a few others in his rotation back then. All those corporate beer brand and pop music group T-shirts were really popular. And “Grease”, Uncle Ty really liked Olivia Newton-John back then. He had a “Grease” T-shirt for sure. Then I remembered, and I reminded him, “You were wearing a Buck Tractor Pulls T-shirt back then, weren’t you?” I was sure of it, nice artwork of a hopped-up farm tractor on the front and “See You at the Buck” across the back.
“No way man,” he retorted, “There’s no way I went down there to waste a Saturday night with that gasoline and gunpowder gang. I would have sooner spent a Saturday night getting a tooth worked on by an angry intoxicated dentist!”
Oh well, everybody has there own idea of a good time.
We’re beginning to worry about Uncle Tyler Dyer. It’s been almost a month since a tornado descended from an eastbound cloud that first passed by Three Mile Island, and from him we’ve heard not a word about it. And the rainfall totals during the past year, well above normal and record setting, but not a peep from him about it. The floods too, and the gusty thunderstorms that either seemed to strike only our town, or would instead let us high and dry while passing off to the north or south. For forty years, from Uncle Ty’s point of view, these phenomena were all attributable to those towers down at Three Mile Island. He would say, “Man, you know the lightning in that thunderstorm was terrible because of T.M.I. You know that, don’t you?”
If you happen to live in the lower Susquehanna valley, you’ve probably heard comments like that at the local diner, taproom, or gathering of family and friends. Many are offered by good-humored folk, in jest, to enliven the conversation. It makes a chat about the weather a bit more exciting. Then to, there are those who became extraordinarily suspicious of the nuclear facility at Three Mile Island after the accident. To them, any deviation from the status quo must be caused by those big towers down there. Even if they don’t fully believe what they’re saying, it matters that they don’t miss the chance to get in a jab, even if it’s a glancing one. That’s Uncle Ty. He sees that plant in a different light than we do, from a different perspective. To him, Three Mile Island is the ultimate symbol of corporate evil. It’s not about the fuel used to operate the reactor. The invisible threat of radioactivity is a metaphor for the secretive operations of sinister big business. Those towers are a collection of monoliths representing greed, interlocking corporate directorships, and immunity from accountability. And no one is going to change his mind.
Everyone has their own perception of Three Mile Island.
If you remember reading, watching, or listening to news reports in the weeks and months following the accident at Three Mile Island, you recall stories from farmers and other residents living in the vicinity of the plant who described diverse irregularities in the health of domestic animals and in populations of wildlife there. For some, these reports left a lasting impression of conditions near the site of the accident.
The Pennsylvania Department of Agriculture, the Environmental Protection Agency, and the Nuclear Regulator Commission conducted an investigation into these reports. Because the levels of radiation released during the accident were barely above background levels, it was going to be difficult to detect any changes in animals or plants that could be definitively linked to operations at Three Mile Island or the accident there.
Upon evaluating cases for which sufficient data had been preserved or animals were available for examination, investigators failed to find any animal deaths, injuries, diseases, deformities, or stillborn young caused by known effects of ionizing radiation exposure. Anemic conditions would have been expected in animals exposed to significant doses of radiation, but cases of anemia were not found. For the animal fatalities reported, their numbers generally fell within the expected mortality rates for breeding, raising, and keeping the species involved. For the cases examined, no link could be made to exposure to ionizing radiation or byproducts released during the operation of T.M.I. or the accident at Unit 2. Instead of a pattern of mortality and illness consistent with ionizing radiation exposure, investigators instead found a wide-variety of problems considered common to animal keeping.
During the investigation, some of the causes for domestic animal afflictions were identified and, when possible, proper remedies were recommended. Animal husbandry errors, accidents, and disease accounted for most of the deaths, disabilities, and reproduction failures in domestic animals. The occurrence of stillborn or deformed pets was attributed to a variety of diseases and developmental problems that are frequently associated with the symptoms described by pet owners. Poultry eggs that failed to hatch were believed to be infertile or were not maintained at the proper temperature during incubation. Many of the physical ailments in adult dairy cows were traced to mineral deficiencies in the feed. Cases of rickets were found among steers at two different farms. Supplements mitigated these abnormalities in the involved herds. Some cows were found to be suffering from bacterial or viral infections. A few dairy animals had developed mastitis, an inflammation often caused by bacterial infection of the udders. Following diagnosis, herdsmen were able to initiate treatment. Among livestock, fertility and reproductive deficiencies were generally traced to nutritional shortcomings or disease. Those farmers needing further help troubleshooting breeding difficulties were referred to the Pennsylvania Department of Agriculture’s Diagnostic Lab.
The majority of people not living in the lower Susquehanna valley at the time paid little attention to the results of the investigations. Such reports are often lengthy and boring, not as exciting as the stories of mutants and catastrophe, and not as memorable. Naturally, the closer you lived to T.M.I., the more informed you probably were about it; you knew first-hand how life was both before and after the accident. Those living elsewhere were sometimes left with exaggerated recollections based upon those initial news stories from the scene.
While traveling some years ago, Uncle Ty was astounded by the perception folks from outside Pennsylvania had of the place he calls home. He told us of one incident in particular. Uncle Ty had gone to the South Bronx in New York City to participate in an “End the Violence” protest. Gunfire and murder were an occurrence of epidemic proportions on street corners there at the time. It turned out that the protest was a poorly attended flop. It happened to be Bat Day at Yankee Stadium, so everyone had gone there instead. During his extended lunch break, Uncle Ty struck up a conversation with a local, a likeable public safety worker who lived and worked in the South Bronx. Ty expressed some sympathy for the stressful conditions the fellow had to endure as a resident there. The guy appreciated his sentiments, but didn’t think he had it too tough. When Ty told him that his home was near Three Mile Island, the guy shook his head in pity and said, “yeah, I hear it’s pretty bad out there, all the two-headed cows walkin’ around and s…”. A guy from one of the most dangerous neighborhoods in the country felt really sorry for him. Even Uncle Ty was caught off guard by that one, but it wasn’t the last time he heard it either.
Today, Uncle Ty has us all pondering. Has he given up on Three Mile Island’s grand towers as the primary factor affecting all meteorological irregularities in the lower Susquehanna? Will we ever hear of a cooling tower induced drought again? What will he turn to? It’ll have to be something big. A causative force that no one can quite prove or disprove, mysterious enough to keep everyone guessing if he really knows something no one else knows. I wonder what it’ll be. No matter what it is, it just won’t be the same as hearing, “Man, don’t you know? T.M.I. did it.”
This two-head calf specimen from the lower Susquehanna valley has been in the natural history collection at the North Museum, Lancaster, PA, since long before the construction of Three Mile Island’s nuclear generating facility and reactors began.
SOURCES
Gears, G. E., G. Laroche, et al. (1980) Investigations of Reported Plant and Animal Health Effects in the Three Mile Island Area. U.S. Environmental Protection Agency. Las Vegas, NV.
Severe thunderstorms with hail, torrential rain, and flooding passed through the lower Susquehanna valley this evening. The National Weather Service in State College issued a warning for a radar-indicated tornado shown crossing the Susquehanna River downstream of Conewago Falls at 6:55 P.M. E.D.T. The rascal revealed itself about ten minutes later.
At 7:05 P.M. E.D.T., this tornado descended to within 500 to 1000 feet of ground level six miles east of Conewago Falls above Elizabethtown in Lancaster County. There was strong rotation in the warm updraft (seen above the red house) and a short-lived cool downdraft descending toward the ground (dark cloud mass above the tan-colored house). Fortunately, prior to getting wrapped up tight, the consolidating vortex dissipated and the clouds retreated skyward while the storm continued to the east.
The staff at a retirement community west of Elizabethtown was on the alert and had the fortitude to quickly sound a warning siren. It was howling away as this image was taken. What could have been a disaster was instead a spectacular close call.
A sixteen year-old skinny kid driving a Ford Pinto on a Saturday afternoon in late March, 1979, might be perceived by some observers as a metaphor for the accident at Three Mile Island on that same day. When experiencing a rear-end collision, the fuel tank on these little compact cars had been known to explode, sometimes with fatal consequences. They quickly gained a reputation as a deadly hazard on the highway. Despite a recall and engineering fix to prevent the fuel tank from failing, the Pinto remained cursed, and it was henceforth looked upon as a dangerous creation of man that best be avoided if you wished to remain in good health.
For a sixteen year-old, a Pinto functioned just fine as a frugal form of transportation. So in a hideous limey-yellow one, a kid showed up at the Three Mile Island Observation Center to have a look around. There, hundreds of photographers, reporters, and journalists had gathered to try for their angle on the latest news from the accident scene. Cars and news vans lined the state road, Pennsylvania Route 441, in front of the facility. Anything that moved was photographed and interviewed. The story of the day, March 31, 1979, was the impending explosion of the hydrogen gas bubble in the Unit 2 reactor. It was the sensation that they had waited for.
By Saturday, the N.R.C. was growing concerned about the potential of a hydrogen explosion within the Unit 2 reactor. Hydrogen was formed early in the accident when hot steam in the high-temperature core reacted with the zirconium alloy in the fuel rod cladding and produced primarily zirconium dioxide and hydrogen gas. Some of this gas had been vented into the reactor containment building. There, it mixed with atmospheric oxygen and ignited when a block valve switch was operated during the late morning of day one. Operators recalled hearing a “whooshing” sound just after flipping the switch. It is believed they did not really hear the explosion or burn-off of the gas, but rather the activation of a water spray system in the building in response to it.
The N.R.C. learned on Friday of this event that had occurred two days earlier. Harold Denton wanted to know if radiolysis of water inside the reactor was producing additional hydrogen and, more critically, oxygen. Many in the N.R.C. were convinced by their calculations that enough oxygen could be produced in the coming days to make the existing hydrogen bubble explosive. Denton wanted to know for sure, and ordered a team to enlist outside help to determine a timeline for this radiolysis. He also assigned a team to determine the parameters and details for a possible explosion.
Meanwhile, this story had gone public. Upon hearing the words “nuclear” and “explosion” together in news reports, the memories of old Civil Defense promotions came back to haunt local residents, and the nation. For many, the horrific image of a nuclear explosion had been projected into their perception of the accident. An explosion similar to an atomic bomb was not possible in the reactors of the type used for energy production in the United States, but few sleep well with visions of mushroom clouds dancing in their heads. For those on the fence deciding whether to stay or go, this was it, the last straw. In response to these broadcasts, more residents left the lower Susquehanna region on Saturday. As they went out, press personnel moved in, many setting up camp at the Three Mile Island Observation Center.
At 2:45 P.M., reporters at N.R.C. headquarters in Bethesda were told that a 10 to 20 mile evacuation might be necessary as a precaution if the decision was made to attempt to force the hydrogen bubble out of the reactor.
An Associated Press story went public at 8:23 P.M. quoting N.R.C. officials as saying that the hydrogen bubble could explode spontaneously.
This information kept local Civil Defense personnel up through the night answering phone calls from the worried residents who remained in their homes. They wanted to know what to do, but the local offices and P.E.M.A. were getting very little advice from the Lieutenant Governor’s and Governor’s offices. The state B.R.P. was still providing them with radiation information, but beyond that, Civil Defense offices were on their own for the night.
Harold Denton, being informed that President Carter was coming to Three Mile Island the next day, wanted things clarified. He told his deputy Victor Stello, Jr. to solicit sources outside the N.R.C. on the oxygen issue. Stello had fielded a call from the White House at about 9:00 P.M.. In response to the A.P. story, he told a presidential aide that he did not share the concern of others at the N.R.C. regarding the production of oxygen in the reactor. He and some engineers at Babcock & Wilcox, designers of the reactor, were among the few who shared this opinion. (Also, engineers at Babcock & Wilcox analyzing the effects of an explosion, should one occur, were confident that water and steam, if maintained in the pressurized reactor containment vessel, would reduce the pressure of an explosion to within the capabilities of the vessel to contain it.)
On Sunday morning, April 1, 1979, Victor Stello made his case to Harold Denton explaining why he thought there would be no hydrogen explosion in the Unit 2 reactor. He told Denton that pressurized water reactors like TMI-2 routinely have free hydrogen circulating in the coolant. The majority of oxygen produced by radiolysis would bind with this hydrogen and simply make more water.
President Carter and First Lady Rosalynn Carter aboard the Marine One helicopter en route from the White House to Harrisburg International Airport on Sunday, April 1, 1979. (White House Staff Photo- National Archives)
Just minutes before the President landed at the Air National Guard facility at Harrisburg International Airport at 1:00 P.M., the N.R.C.’s Joseph Hendrie and Roger Mattson, who had been researching the explosion question, arrived at a hangar there to present their case to Denton.
Quoted in the “Report of the President’s Commission on the Accident at Three Mile Island”, Mattson described the scene:
“…And Stello tells me I am crazy, that he doesn’t believe it, and he thinks we’ve made an error in the rate of calculation…Stello says we’re nuts and poor Harold is there, he’s got to meet with the President in 5 minutes and tell it like it is. And here he is. His two experts are not together. One comes armed to the teeth with all these national laboratories and Navy reactor people and high faluting PhDs around the country, saying this is what it is and this is the best summary. And his other (the operating reactors division) director saying, “I don’t believe it. I can’t prove it yet, but I don’t believe it. I think it’s wrong.”…”
View from Marine One as the President and First Lady pass over Conewago Falls and approach the Three Mile Island Generating Facility. Marine One would land just upriver at Harrisburg International Airport. (White House Staff Photo- National Archives)Harold Denton (left) briefs President Jimmy Carter and Pennsylvania Governor Richard Thornburgh. Denton’s deputy, Victor Stello, Jr., looks on. (White House Staff Photo- National Archives)
President Jimmy Carter was no stranger to nuclear reactors, or reactor accidents for that matter. A 1947 graduate of the United States Naval Academy, Carter eventually worked his way into Captain (later Admiral) Hyman Rickover’s nuclear command. In 1952, Rickover (known as the father of the Nuclear Navy) ordered the 28 year-old Lieutenant Carter, then assigned to the Naval Reactors Branch at the U. S. Atomic Energy Commission, to the scene of a partial meltdown of a research reactor at Chalk River Laboratories in Ontario, Canada.
There, Carter led a team of 23 men. Their job was to shut down and dismantle the damaged reactor. They built a mock-up of the reactor on a tennis court and practiced taking turns performing the tasks to complete the job. This model would be used to track the progress of the project in the actual reactor. When a bolt, nut, or other part was removed in the real reactor core, it would be removed from the model as well.
Following these preparations, men suited up in protective gear and were lowered into the reactor, one man at a time, to do the work. Each man in the rotation was permitted to be in the reactor for only ninety seconds, then he was hoisted back out. During every one of these short journeys to the core, each worker, including Carter, received a dose equivalent to a year’s worth of allowable radiation today. Carter’s urine was radioactive for six months afterward.
President Carter’s earlier experiences in Rickover’s Navy, particularly at Chalk River, gave him exceptional familiarity with conditions arising from the accident at Three Mile Island in 1979.
The President and his party left their limousines near the east shore gate and entered Three Mile Island by school bus. Denton’s arrival on Friday and Carter’s tour of the plant on Sunday had a calming effect on the anxieties of residents in the lower Susquehanna region. (White House Staff Photo- National Archives)James Floyd, supervisor of Unit 2 operations, explains the situation to the Carters, Governor Thornburgh, and Harold Denton. (White House Staff Photo- National Archives)The President and Governor look over some of the metering devices in the control room. (White House Staff Photo- National Archives)The President and First Lady receive assistance as they shed their protective boots and prepare to leave the plant facility. (White House Staff Photos- National Archives)After returning to the limousines by school bus, the President and his party motorcade to Harrisburg International Airport and the awaiting Marine One helicopter. (White House Staff Photo- National Archives)
Following the briefing of the President and Governor, Stello, Hendrie, and Mattson went back to the N.R.C.’s temporary office to try to rectify the oxygen and explosion problem. After consulting with some additional outside sources, including Westinghouse and General Electric, they had the answer. The hydrogen bubble would NOT explode. It was 3:00 P.M.
At just before 4:00 P.M., there was a new push from the N.R.C. in Bethesda to start an evacuation within two miles of the plant. Chairman Hendrie informed them—there is NO danger of an explosion. The teams in Bethesda would find concurrence with Stello, Hendrie, and Mattson by later that evening. On Monday, the N.R.C. trickled out the good news, but would not outright admit that their calculation errors had caused a near panic. Instead, they claimed that they had been a little too conservative in their estimates.
Shortly following the President’s visit, or during it, the hydrogen bubble began dissipating. The public wasn’t made aware of it until the following day, Monday, April 2. By then, operators for the utility reported that it was nearly gone. No direct action had been taken to get rid of the bubble, its disappearance was mysterious, yet welcome.
Nobody knows how many people evacuated the lower Susquehanna valley during the accident. It is generally believed that over 100,000 left for at least the weekend. Some communities, such as Goldsboro, a small town overlooking Three Mile Island’s reactors from the York County side of the Susquehanna, may have experienced evacuation rates approaching ninety percent. In the majority of areas more distant from the plant, the rate was well below fifty percent. Most of those who left their homes began returning as schools reopened during the mid-week.
During that first weekend, the press was angling to get officials to speculate on the probability of the occurrence of a catastrophic core meltdown. No one had realized that the meltdown had already happened, on day one. It was determined in 1987 that in excess of half of the more than 100 tons of uranium oxide fuel had melted during that first morning. In 1989, 20 tons of molten fuel was discovered to have flowed to the bottom of the reactor vessel and solidified into a slag-like mass there. Fortunately, Unit 2’s pressurized reactor vessel had kept the catastrophic core meltdown contained within its five-inch-thick steel structure.
Crews on Three Mile Island worked faithfully to manage gases and continue the cooling of the reactor core. Cold shutdown of the reactor (reduction of temperatures to below the atmospheric boiling point of water) would take another week, the full cleanup and de-fueling would take more than a decade. Unit 2 was placed in monitored storage in 1993, and will be fully decommissioned simultaneously with the Unit 1 reactor when the latter is permanently taken out of service.
On the day of his visit to Three Mile Island, President Carter signed executive orders activating the Federal Emergency Management Agency (F.E.M.A.), a new entity formed to house Civil Defense and disaster preparedness, with the latter of the two becoming the greater focus of its mission.
Forty years after his visit to Three Mile Island, Jimmy Carter, at age 94 ½ years, had become the longest-lived President in American history. We wish he and Rosalynn many more happy years.
Finally, what shall we think of the risky travels of a sixteen year-old? Was the bigger hazard the act of being inside a Ford Pinto while driving to Three Mile Island on Saturday, March 31, 1979, or was it the act of being at Three Mile Island itself on that afternoon? We’ll let you decide.
SOURCES
Forman, Paul, and Sherman, Roger. 2004. Three Mile Island: The Inside Story. Web presentation based upon Smithsonian National Museum of American History exhibit, as accessed March 28, 2019. https://americanhistory.si.edu/tmi/index.htm
Kemeny, John G., et al. 1979. Report of the President’s Commission on the Accident at Three Mile Island; The Need for Change: The Legacy of TMI. U. S. Government Printing Office, Washington, D.C.
Milnes, Arthur. January 28, 2009. “When Jimmy Carter Faced Radioactivity Head-on”. The Ottawa Citizen.
It was forty years ago today. The civics teacher had a hook on stick, and he was under orders to use it. He was trying his best to draw the water-stained paper blinds down over the tall old single-pane glass windows that covered the length of the outer wall of his west-facing room. You understand, this was not something he was doing of his own accord. He was a veteran educator, one of those teaching the offspring of his students from a previous generation. He was no tyrant merely wanting to deny his pupils the distractions of a beautiful spring day outdoors. He was ordered by the coffee cup brigade in the front office to close the windows and draw the shades. The safety of the students is at stake!
As his third class of the day entered the room, the instructor enlisted the help of a couple of taller students to try to get some of those stubborn window coverings pulled down. No luck. Class would commence with blinds up, down, and in between. Today’s topic: the dangers of nuclear energy. As usual, it was something of an open discussion of current events. All points of view were encouraged.
Few noticed the town fire siren howling away during the first minutes of the oratory. That happened every once in a while, so it wasn’t so remarkable. The class transformed from debate and dialog to a practical demonstration a little while later when fire trucks began circulating through the streets near the school broadcasting muffled incoherent warnings of some sort to the residents of adjacent neighborhoods.
Within moments there was clamor in the hallways as several students were banging locker doors and making off with their wares. Soon the old classroom phone that hung as a decoration on the wall near the doorway began making an obnoxious noise. What does this mean? What should we do? It never made a sound before. The dedicated educator walked over and picked up the receiver. He timidly said, “Hello?” He listened carefully, acknowledging the caller from time to time, then he said, “O.K.” After hanging up the little-used device, he walked over to a startled girl and simply told her to gather things and report to the office, one of her parents was here to pick her up.
The old sage walked back to the lectern and just stared around at the quiet faces in the room , not a word was said until the phone rang again. He looked over toward a skinny sixteen year-old kid, a late-bloomer, seated near the half-shaded windows and quietly said, “Mr. C—, you have duties to perform, don’t you?, you may leave.” Then he turned to answer the phone for the second time. The skinny kid departed the school building posthaste.
Three Mile Island Unit 2 (left) in monitored storage. Three Mile Island Unit 1 (right) generating electricity. March 28, 2019.
Since the beginning of the accident, operators of the Unit 2 reactor had been spending a considerable share of their time and effort coping with noncondensible gas in Unit 2’s coolant system. Not only was there growing concern that a build-up of Hydrogen around the top of the reactor core was preventing coolant from reaching the fuel assemblies, but gas was causing problems in other portions of the cooling system as well. One component in particular, a make-up tank used to store water that is used as needed to increase the volume of coolant in the primary cooling system, was of concern in the early morning hours of Friday, March 30, 1979. Its relief valve had activated at least once due to excessive pressure. Gauges read that gases had displaced all of the water from the tank.
Just before 7:00 A.M., operators decided to open a valve to purge the radioactive gases from the make-up tank into the waste gas decay tanks where it is collected and stored by design. The venting began at 7:10 A.M. Aware that a header leaks in this system, and that any leaked gas will enter the auxiliary building and be discharged to the atmosphere from its vent stack, a helicopter monitoring flight is requested to collect samples above the plant and its perimeter. Almost an hour into the venting process, at 8:01 A.M., a radiation reading of 1,200 millirems per hour (mr/hr) is measured 130 feet directly above the vent stack. A reading of only 14 mr/hr was taken along the boundary of the facility site. This was an expectable set of readings. During a short venting procedure involving the make-up tank on the previous day, a sampling flight measured 3,000 mr/hr fifteen feet above the stack .
Confident that they can now keep gas accumulation in the make-up tank under control by “puffing” it clear on a regular basis, and again having the ability to use the make-up tank to equalize coolant levels, the process is a success. The operators are on to the next step as they strive to get the reactor into a cold shutdown.
Friday’s memorable troubles resulted from a series of inaccurate reports of the 1,200 mr/hr reading taken above the auxiliary building vent stack. For the next ninety minutes, the 1,200 mr/hr figure shot like lightening through a chain of phone calls that left Three Mile Island and made its way through state-level and county-level offices and found smooth sailing through the Nuclear Regulatory Commission (N.R.C.) and landed right in the middle of meeting of the latter in Bethesda, Maryland.
But first, at 8:45 A.M., a Telex message arrives at the N.R.C.’s Incident Response Center:
“The seal return to the makeup tanks was causing excessive gas pressures in the makeup tank which was directed to the waste gas decay tanks which were full. The waste gas tanks were being released to the stack. Pennsylvania Civil Defense was being notified by Licensee.”
This errant message indicates that the highly radioactive contents of the waste gas decay tanks, which are NOT full, can be expected to vent from Three Mile Island with some regularity for the foreseeable future. At 9:00 A.M., the N.R.C.’s Lake Barrett carries the Telex into a meeting of the agency’s Executive Management Team (E.M.T.). Alarmed by the news, they ask Barrett to calculate what an off-site radiation dose might be with the anticipated releases. Ironically, Barrett arrives at a figure of 1,200 mr/hr for a person at the site boundary, a value exceeding the Environmental Protection Agency (E.P.A.) threshold for evacuation of sensitive persons. Within minutes, the E.M.T. receives a phone call from Karl Abraham, the N.R.C. press officer at Governor Richard Thornburgh’s office in Harrisburg. He’s on the speakerphone and wants to know if the reports of 1,200 mr/hr readings above the “cooling towers” are true. This is the first the E.M.T. has heard of the 1,200 mr/hr number at the site, and because it matches Barrett’s calculation for off-site releases from full waste gas decay tanks, they assume it to be an off-site number and forget that Abraham was asking a question. Following a discussion, Harold Denton, Director of Reactor Regulation, orders that a recommendation for evacuation out to ten miles in the direction of the plume be given to the Pennsylvania Emergency Management Agency (P.E.M.A.), the state-level Civil Defense agency. This recommendation is delivered at 9:15 A.M. Unfortunately, the location of the 1,200 mr/hr reading was not verified beforehand.
In Harrisburg, Margaret Reilly of Pennsylvania’s Bureau of Radiation Protection (B.R.P.) was trying to verify the N.R.C.’s reasons for the evacuation recommendation. There was some ire because P.E.M.A. received the recommendation instead of the B.R.P., or, better yet, Governor Thornburgh himself. Information available to Pennsylvania agencies showed no reason to evacuate.
Dutifully acting on the N.R.C.’s recommendation, the state notifies Dauphin County Civil Defense, telling them to expect an evacuation order from the Governor within five minutes. The mild temperatures on this Friday were due to a steady wind from the southwest, putting communities in Dauphin County within any possible plume from the Three Mile Island Unit 2 facility. It appeared that communities in Dauphin County, including the city of Harrisburg, would comprise the majority of the evacuation zone. Fire companies, municipal officials, local Civil Defense directors, and others were alerted. Announcements on Harrisburg’s WHP radio advised citizens within five miles of T.M.I. to make preparations and gather supplies for a possible evacuation. The cat was out of the bag.
Governor Thornburgh was very cautious, possessing an understanding of the risks to the public that an evacuation order could cause. He would later be quoted, “In Pennsylvania, P.E.M.A.’s role is to manage the emergency, not to recommend evacuation. P.E.M.A. mentality (during the T.M.I.-2 accident) was akin to being all dressed up with no place to go—leaning forward in the trenches. We had to be careful about that attitude.” Thornburgh knew that ordering an evacuation meant moving patients in health care facilities, possibly at great risk to them. He knew too, that evacuation meant putting helmets in the street—the National Guard.
The Bureau of Radiation Protection had checked the site and conferred with the N.R.C. in Bethesda and was convinced that an evacuation was not necessary. Because of the public broadcasts, phone lines were jammed, so nuclear engineers from B.R.P. are hurriedly en route to the Governor’s office and P.E.M.A. to deliver the facts in person. It’s 9:45 A.M.
At the same time in Bethesda, the E.M.T. had learned that the 1,200 mr/hr reading was not from off-site, but from directly above the vent stack. They were also made aware that the venting had not come from the waste gas decay tanks, but from the make-up tank. And finally, they learned that the waste gas decay tanks were not full, but were accepting gases from the make-up tank as designed. By 10:00 A.M., they rescinded their evacuation order—about the same time that Governor Thornburgh countermanded it.
Too late. By this time people were getting out of town. Schools were overwhelmed as parents showed up to pull their children out of class, one by one at first, then in droves. Sirens were sounding. Broadcasts were telling people to close blinds and windows and remain indoors. The Three Mile Island Unit 2 accident was now the biggest news event in the nation.
Governor Thornburg went on WHP radio at 10:25 A.M. to broadcast a message to residents, attempting to rectify some of the contradictions of the morning. Within the hour, President Carter would call the Governor and assure him of the White House’s full support. He told the Governor that he was sending Harold Denton to the scene forthwith. Denton was to “take charge of the site on behalf of the federal government”.
At local Civil Defense offices in the lower Susquehanna valley, there was a continuous flow of telephone calls from concerned citizens, some of them very frightened. They wanted to know what to do. The ball was rolling, and people with families were becoming more and more inclined to leave.
A skinny sixteen year-old volunteer walked into a community fire station in a small town about six miles from Three Mile Island at about 11:00 A.M. There, the town’s mayor and Civil Defense Director were conferring inside the “Civil Defense office”, a coat closet with a desk and ashtray. The phone was in the adjacent closet, which had more desks and ashtrays. The discussion centered around responsibilities for ordering an evacuation. Following the events at the federal and state level earlier in the morning, it was unclear who had the authority and responsibility to order an evacuation.
The scene was tense, the cigarette smoke was rolling out of the closet for hours as phone calls were made and the chain of command was clarified. Evacuation plans were being worked out in case they were needed. Moving patients from hospitals and nursing facilities was a particularly difficult planning challenge to be tackled. The cloud would persist as the chain smoking continued for the next couple of days. (And those plaid double-knit leisure suits with Flintstones neckties—wow!—it’s a good thing there were no photographs taken of this scene.)
Elsewhere inside the fire station, the sixteen year-old lad and some other volunteers collected the radiological monitoring supplies from the blue and white Civil Defense rescue truck. After gathering some fresh batteries, they ventured outdoors and set up a small monitoring station. Lungs clouded by all the chain smoking inside could be clarified out there. Several metering devices were employed in an attempt to detect radiation. The crew remained at their post through late afternoon, keeping a sharp lookout for the fashion police and enjoying the balmy spring air. It was easy work and no radiation was detected.
In the late 1950s, Civil Defense Light-Duty Rescue Vehicles were provided to some of the larger towns in the lower Susquehanna valley. These trucks were fully supplied with tools primarily intended to remove victims from structures collapsed by detonation of a nuclear weapon. They were often operated by fire companies and used for vehicle accidents and other rescues. The hand-held radiation meters provided with these vehicles were not capable of detecting the low radiation levels found outside the plant perimeter during the T.M.I.-2 accident. (National Archives Image)
Following further consultation with the N.R.C., the Governor held a press conference at 12:30 A.M. He advised pregnant women and pre-school age children to leave the area of a five-mile radius around Three Mile Island. He closed the schools and the few students still in the classrooms were on their way home—or to the mountains for an unscheduled spring holiday.
Harold Denton would arrive at Three Mile Island during the mid-afternoon. Denton found inadequate facilities and communications (no cellular telephone in 1979!) at the T.M.I. Observation Center building where other N.R.C. personnel had set up temporarily. This facility on the east shore of the Susquehanna overlooking the plant was now overrun by scores and soon hundreds of reporters, so Denton set up his base in a home offered by a Met-Ed employee just across the street. He set up his temporary office in the living room, complete with a direct line to the White House. Denton would have his work cut out for him; the hydrogen gas bubble was becoming an increasing concern and the press was storming over the possibility of a catastrophic meltdown. The situation was serious—there would be no BINGO in the fire halls this weekend.
Civil Defense promotions scared the living wits out of a whole generation of parents, then horrified their kids too. Those who grew up with the messages and drills remember them well. (National Archives Image)People had to wonder if Civil Defense knew what in hell they were talking about. Look closely. When the “BIG ONE” comes we’re planning to take cover in the nearly airtight “finished” cellar, eat potato chips, and bounce around on a trampoline like maniacs while mom cooks canned Spam on a GAS CAMPING STOVE! At least we won’t need any sleeping pills. (National Archives Image)After years of being terrorized by this public outreach stuff, what appeared to be the “BIG ONE” came on the morning of Friday, March 30, 1979, and the bureaucracy acted like it was the first time they’d ever heard of any of it. The public perceived the apparent compromise of the chain of command. As the contradicting announcements escalated during the third day, residents gave the utility and government a vote of “no confidence”, and they did that voting with their feet. They decided to take the fate of their families into their own hands and evacuate, regardless of recommendations from Civil Defense or other entities. Who can blame them? Radiation or no radiation, their trust was eroded and they were leaving. (National Archives Image)
Thanks Mr. H—, wherever you are!
SOURCES
Kemeny, John G., et al. 1979. Report of the President’s Commission on the Accident at Three Mile Island; The Need for Change: The Legacy of TMI. U. S. Government Printing Office, Washington, D.C.
Rogovin, Mitchell, et al. 1980. Three Mile Island: A Report to the Commisssioners and the Public. Nuclear Regulatory Commission.
The Three Mile Island Unit 2 reactor containment building (center) and cooling towers (left) as they appeared this morning, forty years after the accident and partial meltdown. The Unit 1 reactor continues to generate electricity. Its containment building can be seen along the lower left edge of the Pennsylvania Historical and Museum Commission marker. Steam can be seen rising from the Unit 1 cooling tower on the far right (the second tower is hidden by the marker).
Forty years ago, at just about 4:01 A.M. on Wednesday, March 28, 1979, the Unit 2 reactor at the Three Mile Island Nuclear Generating Station on the Susquehanna River at Conewago Falls “scrammed”—the control rods automatically dropped into the reactor core to stop fission. This occurred in response to the automatic opening of the “Pilot-Operated Relief Valve” (P.O.R.V.) on the pressurizer, a tank designed to prevent the boiling of water in the primary cooling system loop that transfers heat energy from the reactor core to the steam generator. The P.O.R.V. activated when steam in the top of the pressurizer tank was compressed by water that was expanding as it increased in temperature while circulating within the primary cooling system loop.
During normal operating conditions, water in a non-nuclear “secondary loop” is pumped through tubes within the steam generator where it absorbs energy from the hot water in the primary cooling system loop. The heat converts the water in the “secondary loop” to steam for turning the steam turbine and making electricity. At about 36 seconds after 4:00 A.M., a set of pumps “tripped” and stopped feeding water through the “secondary loop” to the steam generator. Within seconds, Unit 2 ceased making electricity. Starting automatically as a failsafe were a set of three “emergency feedwater pumps”, designed to reestablish water flow to the steam generator. A reactor operator verified their start just fourteen seconds after the main pumps “tripped”. Unfortunately, the operator did not notice the panel lights indicating that valves were closed on each of the two lines supplying the steam generator from the emergency pumps. With the “secondary loop” shut down, heat from fission in the reactor core began accumulating within the steam generator and the primary cooling system loop, leading to the P.O.R.V. activation, and the reactor’s “scramming”. The “scram” triggered control rods to drop in 69 tubes among the 36,816 uranium oxide fuel rods to absorb neutrons and stop the chain reaction fission process in the core of Unit 2.
Three Mile Island Unit 2, a pressurized water reactor, used nuclear fission of uranium fuel to heat water circulating in the primary cooling system loop. Within the steam generator, this heat converted water circulating in the low pressure “secondary loop” to steam, which rotated the turbine to drive the generator that produced electricity. Note the “third loop”, which cooled the condenser used to convert steam back to water in the “secondary loop”. Coolant in the “third loop” lost its heat at the base of the cooling towers, then returned to the turbine building for reuse, but did not circulate through the reactor building at any time. (United States Nuclear Regulator Commission Image)
Following the reactor’s “scramming”, an equipment malfunction occurred when the P.O.R.V. failed to automatically close as designed after reducing pressure within the pressurizer vessel on the primary cooling system loop. Unbeknownst to anyone at the time, this equipment malfunction initiated a small “Loss Of Coolant Accident” (L.O.C.A.). Fortunately, the reactor’s High Pressure Injection system (H.P.I.) automatically began pumping water into the primary cooling system to compensate for the loss of coolant through the stuck valve. Even though fission was no longer generating heat, the decaying radioactive materials within the reactor still require continuous cooling until the reactor is brought to cold shutdown.
(Note that the dropping of control rods to effect an automatic scramming immediately reduced the heat output in the core to 160 megawatts, or about 6% of that generated while the fission reaction was occurring. Normally, the heat release rate after the first hour would drop to about 30 megawatts and, over next three hours, to 20 megawatts. This is still a lot of heat—enough to severely damage the fuel assemblies in the core. Twenty megawatts is equivalent to the heat release rate from a big wind-driven apartment fire. It is critical that an uninterrupted flow of cooling water circulates through the core to prevent damage. See the “Riverside Firemen’s Retreat” page on this site to learn how heat release rate applies to the work firefighters do.)
Enter human error, enhanced by insufficient training, missing protocols, and a poorly designed control panel (including, at one point, 100 alarms in simultaneous operation!), and soon the small L.O.C.A. was converted into a destructive meltdown event. An illuminated light on the reactor control panel indicated that a signal had been sent to close the stuck P.O.R.V.; it did not indicate the valve’s position—open or closed. It would be two hours before operators were aware of the stuck valve and would take corrective action to close the back-up “block valve” to stop the leak. Had the H.P.I. system continued operating autonomously throughout this two hour period, no damage to the reactor core would have resulted. However, operators began overriding the emergency H.P.I. system by throttling the flow of 1,000 gallons per minute back to less than 100, hoping to maintain a certain water level in the reactor. This action was inspired by an operator’s doctrine encouraging them not to let the primary cooling system ever “go solid” (fill completely with water). For “extended periods” during the first day of the event, the H.P.I. was throttled back or shut down. It was during these periods that much of the core of the reactor was exposed, resulting in its meltdown.
A television news crew shoots a report marking the 40th anniversary of the accident at Three Mile Island Unit 2 (background). The time was approximately 8:30 A.M.. At about the same time 40 years earlier, word of the incident first leaked to the public.
The Reportof the President’s Commission on the Accident at Three Mile Island reveals how haphazard and unorganized the notifications of key persons and agencies were from the very start of the accident. The mayor of Harrisburg at the time, Paul Doutrich, first heard about the accident when he received a phone call from a radio station in Boston inquiring what he planned to do about the nuclear emergency. They had to fill him in first.
The public gained little if any confidence from clumsy and often contradictory public statements made by the plant operator, regulators, and various other government officials during the first days of the event. The oscillations between dire warnings on one hand, and assurances that there is no need to worry on the other, frightened and angered thousands of people in 1979. Memories of these awkward and inconsistent messages continue to be the dominant recollections for many residents of the lower Susquehanna region to this very day.
Here, for your entertainment pleasure, is how the media and general public first learned of the accident on the morning of March 28, 1979 (quoted from the Report of the President’s Commission on the Accident at Three Mile Island)…
“WKBO, a Harrisburg “Top 40” music station, broke the story of TMI-2 on its 8:25 a.m. newscast. The station’s traffic reporter, known as Captain Dave, uses an automobile equipped with a C.B. radio to gather his information. At about 8:00 a.m., he heard police and fire fighters were mobilizing in Middletown and relayed this to his station. Mike Pintek, WKBO’s news director, called Three Mile Island and asked for a public relations official. He was connected instead with the control room to a man who told him: “I can’t talk now, we’ve got a problem.” The man denied that “there are any fire engines,” and told Pintek to telephone Met Ed’s headquarters in Reading, Pennsylvania.”
By late Wednesday afternoon, the reports from the plant indicated that everything was under control. Day one would end with the residents of the lower Susquehanna area presuming they would hear little more of this event. Then came Friday.
SOURCES
Forman, Paul, and Sherman, Roger. 2004. Three Mile Island: The Inside Story. Web presentation based upon Smithsonian National Museum of American History exhibit, as accessed March 28, 2019. https://americanhistory.si.edu/tmi/index.htm
Kemeny, John G., et al. 1979. Report of the President’s Commission on the Accident at Three Mile Island; The Need for Change: The Legacy of TMI. U. S. Government Printing Office. Washington, D.C.
There was a hint of what was to come. If you were out and about before dawn this morning, you may have been lucky enough to hear them passing by high overhead. It was 5:30 A.M. when I opened the door and was greeted by that distinctive nasal whistle. Stepping through the threshold and into the cold, I peered into the starry sky and saw them, their feathers glowing orange in the diffused light from the streets and parking lots below. Their size and snow-white plumage make Tundra Swans one of the few species of migrating birds you’ll ever get to visibly discern in a dark moonless nighttime sky.
The calm air at daybreak and through the morning transitioned to a steady breeze from the south in the afternoon. Could this be it? Would this be that one day in late February or the first half of March each year when waterfowl (and other birds too) seem to take advantage of the favorable wind to initiate an “exodus” and move in conspicuous numbers up the lower Susquehanna valley on their way to breeding grounds in the north? Well, indeed it would be. And with the wind speeding up the parade, an observer at a fixed point on the ground gets to see more birds fly by.
In the late afternoon, an observation location in the Gettysburg Basin about five miles east of Conewago Falls in Lancaster County seemed to be well-aligned with a northwesterly flight path for migrating Tundra Swans. At about 5:30 P.M., the clear sky began clouding over, possibly pushing high-flying birds more readily into view. During the next several hours, over three thousand Tundra Swans passed overhead, flocks continuing to pass for a short time after nightfall. There were more than one thousand Canada Geese, the most numerous species on similar days in previous years. Sometimes on such a day there are numerous ducks. Not today. The timing, location, and conditions put Tundra Swans in the spotlight for this year’s show.
Tundra Swans flying northwest, paralleling the Susquehanna five miles distant.Tundra Swans winter on the Atlantic Coastal Plain and often stage their northbound movements on the Piedmont along the lower Susquehanna River and at the nearby Middle Creek Wildlife Management Area. The birds seen this evening are possibly coming directly from the coast or Chesapeake Bay. With five hours of favorable wind helping them along, covering one hundred miles or more in an afternoon would be no problem.High-flying Tundra Swans on their way to breeding grounds on, you guessed it, the arctic tundra in Alaska and northwestern Canada.Tundra Swans in the largest flocks, sometimes consisting of more than 200 birds, were often detected by their vocalizations as they approached.Tundra Swan flights continued after sunset and nightfall.All of the high-flying migratory Canada Geese seen this evening were on a more northerly course than the northwest-bound swans. These geese probably spent the winter on the Atlantic Coastal Plain near Chesapeake Bay and are now en route to breeding grounds in, you guessed it again, Canada. They are not part of the resident Canada Goose population we see nesting throughout the lower Susquehanna valley.
Other migrants moving concurrently with the waterfowl included Ring-billed Gulls, Herring Gulls (6+), American Robins (50+), Red-winged Blackbirds (500+), and Common Grackles (100+).
Though I’ve only seen such a spectacle only once during a season in recent years, there certainly could be another large flight of ducks, geese, or swans yet to come. The breeze is forecast to continue from southerly directions for at least another day. Keep you eyes skyward, no matter where you might happen to be in the lower Susquehanna valley. These or other migratory species may put on another show, a “big day”, just for you.
If you were a regular visitor to this website during the autumn of 2017, you will recall the proliferation of posts detailing the bird migration at Conewago Falls during the season. The lookout site among the Pothole Rocks remained high and dry for most of the count’s duration.
In the fall of 2018, those lookout rocks were never to be seen. There was to be no safe perch for a would-be observer. There was no attempt to conduct a tally of passing migrants. If you live in the lower Susquehanna River drainage basin, you know why—rain—record setting rain.
Annual precipitation during 2018 as indicated by radar. Note the extensive areas in pink. They received in excess of 70 inches of precipitation during 2018, much of it during the second half of the year. (NOAA/National Weather Service image)Average annual rainfall. Most of the lower Susquehanna drainage basin receives an average of just over 40 inches of rain each year. (NOAA/National Weather Service image)Departure from normal annual precipitation totals. Note the extensive areas of greater than 20 inches of precipitation above normal (pink). Severe flooding occurred on many streams during numerous events throughout the second half of 2018. Note the closer to normal totals in central New York in the upper Susquehanna watershed. The lesser amounts of rain there and the localized pattern of the flooding events in Pennsylvania prevented the main stem of the lower Susquehanna from experiencing catastrophic high water in 2018. (NOAA/National Weather Service image) Though there has been no severe flooding, frequent rain events in the Susquehanna watershed have maintained persistently high river levels in Conewago Falls. Pothole Rocks seen here on December 9 during an ebb in the flow were soon inundated again as rains fell in the Susquehanna basin upstream. Of course, each time the river receded it left behind a fresh pile of plastic garbage. What didn’t end up on the shoreline found its way to Chesapeake Bay…then on to the Atlantic. Is that your cooler?
Fifty years ago, the crew of Apollo 8 became the first humans to leave Earth and journey to its closest celestial body, the Moon. Launching on the morning of December 21, 1968, they were the first to enter space from atop the powerful and complex Saturn V rocket. Their eyes would be the first to see the Earth as an entire sphere and to orbit the Moon and observe its obscure far side. For many back home, they changed not only the way we understand the Moon, but how we perceive the uniqueness and fragility of Earth.
On December 23, 1968, the crew of Apollo 8 transmitted this black-and-white television image of Earth to an awe-struck global audience back home. Astronauts Frank Borman, Jim Lovell, and Bill Anders were the first of only 24 persons to date who have observed, with their own eyes, the entire disk of the planet, seen here from 176,533 miles during their outbound journey to orbit the Moon. (NASA Image)Striking color photographs were processed and distributed following the return of Apollo 8’s crew from their successful Christmas Eve orbits of the Moon. Exposed while outbound on December 22, 1968, this spectacular image includes the Americas, the Atlantic Ocean, and western Africa. Taken within a day of the Northern Hemisphere’s Winter Solstice, the photograph clearly shows the shadow of darkness draped across the Arctic region. (Science & Analysis Laboratory, Johnson Space Center, NASA Image) Photographed by astronaut Bill Anders, the well-known “Earthrise” image reveals our blue world as seen from the Apollo 8 Command Module which at the time was emerging from the opposite side of the moon during one of its Christmas Eve lunar orbits. (NASA Image)
Said Command Module Pilot Jim Lovell during a televised broadcast from lunar orbit on Christmas Eve half a century ago, “The vast loneliness up here of the Moon is awe-inspiring, and it makes you realize just what you have back there on Earth. The Earth from here is a grand oasis in the big vastness of space.”
Second Mountain Hawk Watch is located on a ridge top along the northern edge of the Fort Indiantown Gap Military Reservation and the southern edge of State Game Lands 211 in Lebanon County, Pennsylvania. The valley on the north side of the ridge, also known as St. Anthony’s Wilderness, is drained to the Susquehanna by Stony Creek. The valley to the south is drained toward the river by Indiantown Run, a tributary of Swatara Creek.
The hawk watch is able to operate at this prime location for observing the autumn migration of birds, butterflies, dragonflies, and bats through the courtesy of the Pennsylvania Game Commission and the Garrison Commander at Fort Indiantown Gap. The Second Mountain Hawk Watch Association is a non-profit organization that staffs the count site daily throughout the season and reports data to the North American Hawk Watch Association (posted daily at hawkcount.org).
Today, Second Mountain Hawk Watch was populated by observers who enjoyed today’s break in the rainy weather with a visit to the lookout to see what birds might be on the move. All were anxiously awaiting a big flight of Broad-winged Hawks, a forest-dwelling Neotropical species that often travels back to its wintering grounds in groups exceeding one hundred birds. Each autumn, many inland hawk watches in the northeast experience at least one day in mid-September with a Broad-winged Hawk count exceeding 1,000 birds. They are an early-season migrant and today’s southeast winds ahead of the remnants of Hurricane Florence (currently in the Carolinas) could push southwest-heading “Broad-wings” out of the Piedmont Province and into the Ridge and Valley Province for a pass by the Second Mountain lookout.
The flight turned out to be steady through the day with over three hundred Broad-winged Hawks sighted. The largest group consisted of several dozen birds. We would hope there are probably many more yet to come after the Florence rains pass through the northeast and out to sea by mid-week. Also seen today were Bald Eagles, Ospreys, American Kestrels, and a migrating Red-headed Woodpecker.
Migrating Broad-winged Hawks circle on a thermal updraft above Second Mountain Hawk Watch to gain altitude before gliding away to the southwest.
Migrating insects included Monarch butterflies, and the three commonest species of migratory dragonflies: Wandering Glider, Black Saddlebags, and Common Green Darner. The Common Green Darners swarmed the lookout by the dozens late in the afternoon and attracted a couple of American Kestrels, which had apparently set down from a day of migration. American Kestrels and Broad-winged Hawks feed upon dragonflies and often migrate in tandem with them for at least a portion of their journey.
Still later, as the last of the Broad-winged Hawks descended from great heights and began passing by just above the trees looking for a place to settle down, a most unwelcome visitor arrived at the lookout. It glided in from the St. Anthony’s Wilderness side of the ridge on showy crimson-red wings, then became nearly indiscernible from gray tree bark when it landed on a limb. It was the dreaded and potentially invasive Spotted Lanternfly (Lycorma delicatula). This large leafhopper is native to Asia and was first discovered in North America in the Oley Valley of eastern Berks County, Pennsylvania in 2014. The larval stage is exceptionally damaging to cultivated grape and orchard crops. It poses a threat to forest trees as well. Despite efforts to contain the species through quarantine and other methods, it’s obviously spreading quickly. Here on the Second Mountain lookout, we know that wind has a huge influence on the movement of birds and insects. The east and southeast winds we’ve experienced for nearly a week may be carrying Spotted Lanternflies well out of their most recent range and into the forests of the Ridge and Valley Province. We do know for certain that the Spotted Lanternfly has found its way into the Lower Susquehanna River Watershed.
This adult Spotted Lanternfly landed in a birch tree behind the observers at the Second Mountain Hawk Watch late this afternoon. It was first recognized by its bright red wings as it glided from treetops on the north side of the lookout.
It was a routine occurrence in many communities along tributaries of the lower Susquehanna River during the most recent two months. The rain falls like it’s never going to stop—inches an hour. Soon there is flash flooding along creeks and streams. Roads are quickly inundated. Inevitably, there are motorists caught in the rising waters and emergency crews are summoned to retrieve the victims. When the action settles, sets of saw horses are brought to the scene to barricade the road until waters recede. At certain flood-prone locations, these events are repeated time and again. The police, fire, and Emergency Medical Services crews seem to visit them during every torrential storm—rain, rescue, rinse, and repeat.
We treat our local streams and creeks like open sewers. Think about it. We don’t want rainwater accumulating on our properties. We pipe it away and grade the field, lawn, and pavement to roll it into the neighbor’s lot or into the street—or directly into the waterway. It drops upon us as pure water and we instantly pollute it. It’s a method of diluting all the junk we’ve spread out in its path since the last time it rained. A thunderstorm is the big flush. We don’t seem too concerned about the litter, fertilizer, pesticides, motor fluids, and other consumer waste it takes along with it. Out of sight, out of mind.
Failure to retain and infiltrate stormwater to recharge aquifers can later result in well failures and reduced base flow in streams. (Conoy Creek’s dry streambed in June, 2007)
Perhaps our lack of respect for streams and creeks is the source of our complete ignorance of the function of floodplains.
Floodplains are formed over time as hydraulic forces erode bedrock and soils surrounding a stream to create adequate space to pass flood waters. As floodplains mature they become large enough to reduce flood water velocity and erosion energy. They then function to retain, infiltrate, and evaporate the surplus water from flood events. Microorganisms, plants, and other life forms found in floodplain wetlands, forests, and grasslands purify the water and break down naturally-occurring organic matter. Floodplains are the shock-absorber between us and our waterways. And they’re our largest water treatment facilities.
Why is it then, that whenever a floodplain floods, we seem motivated to do something to fix this error of nature? Man can’t help himself. He has a compulsion to fill the floodplain with any contrivance he can come up with. We dump, pile, fill, pave, pour, form, and build, then build some more. At some point, someone notices a stream in the midst of our new creation. Now it’s polluted and whenever it storms, the darn thing floods into our stuff—worse than ever before. So the project is crowned by another round of dumping, forming, pouring, and building to channelize the stream. Done! Now let’s move all our stuff into our new habitable space.
Natural Floodplain- Over a period of hundreds or thousands of years, the stream (dark blue) has established a natural floodplain including wetlands and forest. In this example, buildings and infrastructure are located outside the zone inundated by high water (light blue) allowing the floodplain to function as an effective water-absorbing buffer.
Impaired Floodplain- Here the natural floodplain has been filled for building (left) and paved for recreation area parking (right). The stream has been channelized. Flood water (light blue) displaced by these alterations is likely to inundate areas not previously impacted by similar events. Additionally, the interference with natural flow will create new erosion points that could seriously damage older infrastructure and properties.
The majority of the towns in the lower Susquehanna valley with streams passing through them have impaired floodplains. In many, the older sections of the town are built on filled floodplain. Some new subdivisions highlight streamside lawns as a sales feature—plenty of room for stockpiling your accoutrements of suburban life. And yes, some new homes are still being built in floodplains.
When high water comes, it drags tons of debris with it. The limbs, leaves, twigs, and trees are broken down by natural processes over time. Nature has mechanisms to quickly cope with these organics. Man’s consumer rubbish is another matter. As the plant material decays, the embedded man-made items, particularly metals, treated lumber, plastics, Styrofoam, and glass, become more evident as an ever-accumulating “garbage soil” in the natural floodplains downstream of these impaired areas. With each storm, some of this mess floats away again to move ever closer to Chesapeake Bay and the Atlantic. Are you following me? That’s our junk from the curb, lawn, highway, or parking lot bobbing around in the world’s oceans.
A shed, mobile home, or house can be inundated or swept away during a flood. Everything inside (household chemicals, gasoline, fuel oil, pesticides, insulation, all those plastics, etc.) instantly pollutes the water. Many communities that rely on the Susquehanna River for drinking water are immediately impacted, including Lancaster, PA and Baltimore, MD. This dumpster was swept away from a parking lot in a floodplain. It rolled in the current, chipping away at the bridge before spilling the rubbish into the muddy water. After the flood receded, the dumpster was found a mile downstream. Its contents are still out there somewhere.
Floodplains along the lower Susquehanna River are blanketed with a layer of flotsam that settles in place as high water recedes. These fresh piles can be several feet deep and stretch for miles. Nature decomposes the organic twigs and driftwood to build soil-enriching humus. However, the plastics and other man-made materials that do not readily decay or do not float away toward the sea during the next flood are incorporated into the alluvium and humus creating a “garbage soil”. Over time, the action of abrasives in the soil will grind small particles of plastics from the larger pieces. These tiny plastics can become suspended in the water column each time the river floods. What will be the long-term impact of this type of pollution?
Anything can be swept away by the powerful hydraulic forces of flowing water. Large objects like this utility trailer can block passages through bridges and escalate flooding problems.
The cost of removing debris often falls upon local government and is shared by taxpayers.
Here, a junked boat dock is snagged on the crest of the York Haven Dam at Conewago Falls. Rising water eventually carried it over the dam and into the falls where it broke up. This and tons of other junk are often removed downstream at the Safe Harbor Dam to prevent damage to turbine equipment. During periods of high water, the utility hauls debris by the truck-load to the local waste authority for disposal. For the owners of garbage like this dock, it’s gone and it’s somebody else’s problem now.
Motor vehicles found after floating away from parking areas in floodplains can create a dangerous dilemma for police, fire, and E.M.S. personnel, particularly when no one witnesses the event. Was someone driving this car or was it vacant when it was swept downstream? Should crews be put at risk to locate possible victims?
Beginning in 1968, participating municipalities, in exchange for having coverage provided to their qualified residents under the National Flood Insurance Program, were required to adopt and enforce a floodplain management ordinance. The program was intended to reduce flood damage and provide flood assistance funded with premiums paid by potential victims. The program now operates with a debt incurred during severe hurricanes. Occurrences of repetitive damage claims and accusations that the program provides an incentive for rebuilding in floodplains have made the National Flood Insurance Program controversial.
In the Lower Susquehanna River Watershed there are municipalities that still permit new construction in floodplains. Others are quite proactive at eliminating new construction in flood-prone zones, and some are working to have buildings removed that are subjected to repeated flooding.
Another Wall— Here’s an example of greed by the owner, engineer, and municipality… placing their financial interests first. The entire floodplain on the north side of this stream was filled, then the wall was erected to contain the material. A financial institution’s office and parking lot was constructed atop the mound. This project has channelized the stream and completely displaced half of the floodplain to a height of 15 to 20 feet. Constructed less than five years ago, the wall failed already and has just been totally reconstructed. The photo reveals how recent flooding has begun a new erosion regime where energy is focused along the base of the wall. Impairment of a floodplain to this degree can lead to flooding upstream of the site and erosion damage to neighboring infrastructure including roads and bridges.
The floodplain along this segment of the lower Swatara Creek in Londonderry Township, Dauphin County is free to flood. Ordinances prohibit new construction here and 14 older houses that repeatedly flooded were purchased, dismantled, and removed using funding from the Federal Emergency Management Agency (F.E.M.A). A riparian buffer was planted and some wetland restorations were incorporated into stormwater management installations along the local highways. When the waters of the Swatara rise, the local municipality closes the roads into the floodplain. Nobody lives or works there anymore, so no one has any reason to enter. There’s no need to rescue stubborn residents who refused advice to evacuate. Sightseers can park and stand on the hill behind the barricades and take all the photographs they like.
A new Pennsylvania Turnpike bridge across Swatara Creek features wide passage for the stream below. Water flowing in the floodplain can pass under the bridge without being channelized toward the path where the stream normally flows in the center. The black asterisk-shaped floats spin on the poles to help deflect debris away from the bridge piers. (flood crest on July 26, 2018)
People are curious when a waterway floods and they want to see it for themselves. Wouldn’t it be wise to anticipate this demand for access by being ready to accommodate these citizens safely? Isn’t a parking lot, picnic area, or manicured park safer and more usable when overlooking the floodplain as opposed to being located in it? Wouldn’t it be a more prudent long-term investment, both financially and ecologically, to develop these improvements on higher ground outside of flood zones?
Now would be a good time to stop the new construction and the rebuilding in floodplains. Aren’t the risks posed to human life, water quality, essential infrastructure, private property, and ecosystems too great to continue?
Isn’t it time to put up the white flag and surrender the floodplains to the floods? That’s why they’re there. Floodplains are for flooding.
It’s sprayed with herbicides. It’s mowed and mangled. It’s ground to shreds with noisy weed-trimmers. It’s scorned and maligned. It’s been targeted for elimination by some governments because it’s undesirable and “noxious”. And it has that four letter word in its name which dooms the fate of any plant that possesses it. It’s the Common Milkweed, and it’s the center of activity in our garden at this time of year. Yep, we said milk-WEED.
Now, you need to understand that our garden is small—less than 2,500 square feet. There is no lawn, and there will be no lawn. We’ll have nothing to do with the lawn nonsense. Those of you who know us, know that the lawn, or anything that looks like lawn, are through.
Anyway, most of the plants in the garden are native species. There are trees, numerous shrubs, some water features with aquatic plants, and filling the sunny margins is a mix of native grassland plants including Common Milkweed. The unusually wet growing season in 2018 has been very kind to these plants. They are still very green and lush. And the animals that rely on them are having a banner year. Have a look…
The flowers of the Common Milkweed were exceptionally fragrant this year. At their peak in early June, their hyacinth-or lilac-like aroma was so prevalent, it drifted into our building and overwhelmed the stink of the neighbor’s filthy dumpster that he had placed 12 feet away from our walls (100 feet from his).
Common Milkweed attracts a pollinating Greenbottle Fly (Lucilia species). The dumpster attracts the invasive House Fly (Musca domestica), carrier of dysentery, typhoid, and other wonderful diseases. Are you following this? Remember as we proceed, milkweed is “noxious”.
Busy Eastern Carpenter Bees (Xylocopa virginica) load up with pollen from the flowers of the Common Milkweed.
A Red Milkweed Beetle (Tetraopes tetrophthalmus) munches on a tender fresh Common Milkweed leaf in mid-June.
Following the pollination of the flowers, seed pods will begin to grow. We trim these off the plants. The removal of the extra weight allows most of the stems to remain erect through stormy weather. You’ll still get new plants from underground runners. As you may have guessed, we’re trying to keep these plants upright and strong to host Monarch butterfly larvae.
We’ve planted a variety of native grassland species to help support the milkweed structurally and to provide a more complete habitat for Monarch butterflies and other native insects. This year, these plants are exceptionally colorful for late-August due to the abundance of rain. The warm season grasses shown below are the four primary species found in the American tall-grass prairies and elsewhere.
Big Bluestem, a native warm-season grass in flower.
Little Bluestem (Schizachyrium scoparium “Fort Indiantown Gap”) in flower. This variety grows on the tank range at the military base where the armored vehicles and prescribed burns substitute for the herd animals and fires of the prairie to prevent succession and allow it to thrive.
Partridge Pea can tolerate sandy soil and is a host plant for vagrant Cloudless Sulphur butterflies.
Black-eyed Susan (Rudbeckia hirta) is a popular native grassland wildflower.
Indiangrass (Sorghastrum nutans) in flower. This and the other native plants shown here are available as seed from Ernst Seed Company in Meadville (PA). They have an unbelievably large selection of indigenous species. You can plant a small plot or acres and acres using really good mixes blended for purposes ranging from reclaiming pipeline right-of-ways and strip mines to naturalizing backyard gardens.
A Red Admiral (Vanessa atalanta) butterfly, a migratory species like the Monarch, on Purple Coneflower (Echinacea purpurea). Yes, it is that Echinacea, the same one used as a supplement and home remedy.
There was Monarch activity in the garden today like we’ve never seen before—and it revolved around milkweed and the companion plants.
A female Monarch laying eggs on a Common Milkweed leaf.
A third instar Monarch caterpillar with Oleander Aphids (Aphis nerii) on a Common Milkweed leaf. Both of these insect species absorb toxins from the milkweed which makes them distasteful to predators.
Fifth instar (left and center) and fourth instar (right) monarch caterpillars devour a Common Milkweed leaf. There were over thirty of these caterpillars in just a ten by ten feet area this morning. We hope that if you’re keeping a habitat for Monarchs, you’re enjoying the same fortune right now!
A slow-moving Monarch stopped for a break after making the circuit to deposit eggs on milkweed throughout the garden.
Third instar (top), fourth instar (right), and fifth instar (left) Monarch caterpillars quickly consume the leaf of a Common Milkweed plant. Caterpillars emerging from eggs deposited today may not have sufficient late-season food to complete the larval segment of their life cycle. Need more milkweed!
After benefiting from the nourishment of the Common Milkweed plant, a fifth instar Monarch caterpillar begins pupation on Big Bluestem grass.
Two hours later, the chrysalis is complete.
Another chrysalis, this one on flowering Switchgrass just two feet away from the previous one. An adult Monarch will emerge from this pupa to become part of what we hope will be the most populated southbound exodus for the species in over five years.
There it is, soon ready to fly away. And all courtesy of the noxious milkweed.
A chrysalis can often be found on man-made objects too. This one is on the rim of a flower pot.
Ornamental flowers can attract adult Monarch butterflies seeking nectar. We’re now more careful to select seeds and plants that have not been treated with neonicotinoid insecticides. There’s growing concern over the impact these compounds may be having on pollinating species of animals. Oh…and we don’t mow, whack, cut, mutilate, or spray herbicides on our milkweed, but you probably figured that out already.
SOURCES
Eaton, Eric R., and Kenn Kaufman. 2007. Kaufman Field Guide to Insects of North America. Houghton Mifflin Company. New York.
It’s been an atypical summer. The lower Susquehanna River valley has been in a cycle of heavy rains for over a month and stream flooding has been a recurring event. At Conewago Falls, the Pothole Rocks have been inundated for weeks. The location used as a lookout for the Autumn Migration Count last fall is at the moment submerged in ten feet of roaring water. Any attempt to tally the migrants which are passing thru in 2018 will thus be delayed indefinitely. Of greater import, the flooding at Conewago Falls is impacting many of the animals and plants there at a critical time in their annual life cycle. Having been displaced from its usual breeding sites on the river, one insect species in particular seems to be omnipresent in upland areas right now, and few people have ever heard of it.
So, you take a cruise in the motorcar to your favorite store and arrive at the sprawling parking lot. Not wishing to have your doors dented or paint chipped because you settled for a space tightly packed among other shopper’s conveyances, you park out there in the “boondocks”. You know the place, the lightly-used portion of the lot where sometimes brush grows from cracks in the asphalt and you must be on alert for impatient consumers who throttle-up to high speeds and dash diagonally across the carefully painted grids on the pavement to reach their favorite parking destination in the front row. Coming to a stop, you take the car out of gear, set the brake, disengage the safety belt, and gather your shopping list. You grasp the door handle and, not wanting to be flattened by one of the aforementioned motorists, you have a look around before exiting.
It was then that you saw the thing, hovering above your shiny bright hood. For a brief moment, it seemed to be peering right through the windshield at you with big reddish-brown eyes. In just a second or two, it turned its whole bronze body ninety degrees to the left and darted away on its cellophane wings. Maybe you didn’t really get a good look at it. It was so fast. But it certainly was odd. Oh well, time to walk inside a grab a few provisions. Away you go.
Upon completion of your shopping, you’re taking the long stroll back to your car and you notice more of these peculiar creatures. Two are coupled together and are hovering above someone’s automobile hood, then they drop down, and the lower of the two taps its abdomen on the paint. You ask yourself, “What are these bizarre things?”
Meet the Wandering Glider (Pantala flavescens), also known as the Globe Wanderer or Globe Skimmer, a wide-ranging dragonfly known to occur on every continent with the exception of Antarctica.
Wandering Gliders sometimes arrive in the lower Susquehanna River valley in large numbers after catching a ride on sustained winds from southerly directions and will often fly and migrate in storm systems. Conditions for such movements have been optimal in our region since mid-July. These dragonflies will often hover above motor vehicle hoods and, after mating, females will deposit eggs upon them, apparently mistaking their glossy surface for small pools of water.
Wandering Gliders travel the globe, and as such are accomplished fliers. Adults spend most of the day on the wing, feeding upon a variety of flying insects. Days ago, I watched several intercepting a swarm of flying ants. As fast as ants left the ground they were grabbed and devoured by the gliders. Wandering Gliders are adept at taking day-flying mosquitos, often zipping stealthily past a person’s head or shoulders to grab one of the little pests—the would-be skeeter victim usually unaware of the whole affair.
Due to their nomadic life history, Wandering Gliders are opportunists when breeding and will lay eggs in most any body of freshwater. Their larvae do not overwinter prior to maturity; adults can be expected in a little more than one to two months. Repetitive flooding in the Lower Susquehanna River Watershed this summer may be reducing the availability of the best local breeding sites for this species—riverine, stream, and floodplain pools of standing water with prey. This may explain why thousands of Wandering Gliders are patrolling parking lots, farmlands, and urban areas this summer. And it’s the likely reason for their use of puddles on asphalt pavement, on rubber roofs, and in fields as places to try to deposit eggs. Unfortunately, they may be as likely to succeed there as they are on your motor vehicle hood.
At this time a year ago, the airspace above the Diabase Pothole Rocks at Conewago Falls was jammed with territorial male Wandering Gliders. Each male hovered at various locations around his breeding territory consisting of pools and water-filled potholes. Intruders would quickly be dispatched from the area, then the male would resume his patrols from a set of repetitively-used hovering positions about six feet above the rocks. Mating and egg-laying continued into late September. The larvae, also called nymphs or naiads, were readily observed in many pools and potholes in early October and the emergence of juveniles was noted in mid-October. The absence of flooding, the mild autumn weather, and the moderation of water temperatures in the pools and potholes courtesy of the sun-drenched diabase boulders helped to extend the 2017 breeding season for Wandering Gliders in Conewago Falls. They aren’t likely to experience the same favor this year, but their great ability to travel and adapt should overcome this momentary misfortune.
A male Wandering Glider aggressively patrols his territory in the Diabase Pothole Rocks Microhabitat at Conewago Falls. August 20, 2017.
A mating pair of Wandering Gliders continue flying non-stop above one of thousands of suitable breeding pools among the Diabase Pothole Rocks at Conewago Falls. September 23, 2017.
A female (bottom)Wandering Glider has deposited eggs in a pool while flying in tandem with a male (top). They’ll do the same thing on your automobile hood! Conewago Falls Diabase Pothole Rocks Microhabitat. September 23, 2017.
Wandering Glider larvae are at the top of the food chain in flooded potholes. As they grew, these dragonfly larvae decimated the mosquito larvae which were abundant there earlier in the summer. October 7, 2017.
A juvenile male Wandering Glider emerges from the pool where it fed and grew as a larva. It remained at water’s edge on the surface of a sun-warmed diabase rock for several hours to dry its wings. It soon flew away to parts unknown, possibly traveling hundreds or thousands of miles. Look carefully at the wings for the beige dash marks on the forward edge near the terminal end. Females lack this marking. Conewago Falls Diabase Pothole Rocks Microhabitat. October 14, 2017.
A Wandering Glider exuviae, the shed exoskeleton of a creature gone, but not forgotten. October 14, 2017.
There are two Conewago Creek systems in the Lower Susquehanna River Watershed. One drains the Gettysburg Basin west of the river, mostly in Adams and York Counties, then flows into the Susquehanna at the base of Conewago Falls. The other drains the Gettysburg Basin east of the river, flowing through Triassic redbeds of the Gettysburg Formation and York Haven Diabase before entering Conewago Falls near the south tip of Three Mile Island. Both Conewago Creeks flow through suburbia, farm, and forest. Both have their capacity to support aquatic life impaired and diminished by nutrient and sediment pollution.
This week, some of the many partners engaged in a long-term collaboration to restore the east shore’s Conewago Creek met to have a look at one of the prime indicators of overall stream habitat health—the fishes. Kristen Kyler of the Lower Susquehanna Initiative organized the effort. Portable backpack-mounted electrofishing units and nets were used by crews to capture, identify, and count the native and non-native fishes at sampling locations which have remained constant since prior to the numerous stream improvement projects which began more than ten years ago. Some of the present-day sample sites were first used following Hurricane Agnes in 1972 by Stambaugh and Denoncourt and pre-date any implementation of sediment and nutrient mitigation practices like cover crops, no-till farming, field terracing, stormwater control, nutrient management, wetland restoration, streambank fencing, renewed forested stream buffers, or modernized wastewater treatment plants. By comparing more recent surveys with this baseline data, it may be possible to discern trends in fish populations resulting not only from conservation practices, but from many other variables which may impact the Conewago Creek Warmwater Stream ecosystem in Dauphin, Lancaster, and Lebanon Counties.
So here they are. Enjoy these shocking fish photos.
Matt Kofroth, Watershed Specialist with the Lancaster County Conservation District, operates the electrofishing wand in Conewago Creek while his team members prepare to net and collect momentarily-stunned fish. Three other electrofishing units operated by staff from the Susquehanna River Basin Commission and aided by teams of netters were in action at other sample locations along the Conewago on this day.
Really big fish, such as this Common Carp (Cyprinus carpio), were identified, counted, and immediately returned to the water downstream of the advancing electrofishing team. Koi of the garden pond are a familiar variety of Common Carp, a native of Asia.
Other fish, such as the Swallowtail Shiner, Redbreast Sunfish (Lepomis auritus), Fallfish, and suckers seen here, were placed in a sorting tank.
Fallfish (Semotilus corporalis) are very active and require plenty of dissolved oxygen in the water to survive. Fallfish, Rainbow Trout (Oncorhynchus mykiss), and Smallmouth Bass (Micropterus dolomieu) were quickly identified and removed from the sorting tank for release back into the stream. Other larger, but less active fish, including suckers, quickly followed.
Small fish like minnows were removed from the sorting tank for a closer look in a hand-held viewing tank. This Fathead Minnow (Pimephales promelas) was identified, added to the tally sheet, and released back into the Conewago. The Fathead Minnow is not native to the Susquehanna drainage. It is the minnow most frequently sold as bait by vendors.
A breeding condition male Bluntnose Minnow (Pimephales notatus).
The Cutlips Minnow (Exoglossum maxillingua) is a resident of clear rocky streams. Of the more than 30 species collected during the day, two native species which are classified as intolerant of persisting stream impairment were found: Cutlips Minnow and Swallowtail Shiner.
This young River Chub (Nocomis micropogon) is losing its side stripe. It will be at least twice as large at adulthood.
The Eastern Blacknose Dace (Rhinichthys atratulus) is found in clear water over pebble and stone substrate..
The Longnose Dace (Rhinichthys cataractae) is another species of pebbly rocky streams.
A juvenile Golden Shiner (Notemigonus crysoleucas). Adults lack the side stripe and grow to the size of a sunfish.
A Swallowtail Shiner (Notropis procne) and a very young White Sucker (Catostomus commersonii) in the upper left of the tank.
A Spotfin Shiner (Cyprinella spiloptera).
A breeding male Spotfin Shiner. Show-off!
The Margined Madtom (Noturus insignis) is a small native catfish of pebbly streams.
The Banded Killifish (Fundulus diaphanus) is adept at feeding upon insects, including mosquitos.
A young Rock Bass (Ambloplites rupestris). This species was introduced to the Susquehanna and its tributaries.
The Greenside Darter (Etheostoma blennioides) is not native to the Susquehanna basin. The species colonized the Conewago Creek (east) from introduced local populations within the last five years.
The Tessellated Darter (Etheostoma olmstedi) is a native inhabitant of the Susquehanna and its tributaries.
The stars of the day were the American Eels (Anguilla rostrata).
After collection, each eel was measured and weighed using a scale and dry bucket. This specimen checked in at 20 inches and one pound before being released.
Prior to the construction of large dams, American Eels were plentiful in the Susquehanna and its tributaries, including the Conewago. They’ve since been rarities for more than half a century. Now they’re getting a lift.
American Eels serve as an intermediate host for the microscopic parasitic glochidia (larvae) of the Eastern Elliptio (Elliptio complanata), a declining native freshwater mussel of the Lower Susquehanna River Watershed. While feeding on their host (usually in its gills), the glochidia cause little injury and soon drop off to continue growth, often having assured distribution of their species by accepting the free ride. Freshwater mussels are filter feeders and improve water quality. They grow slowly and can live for decades.
American Eels are a catadromous species, starting life as tiny glass eels in the saltwater of the Atlantic Ocean, then migrating to tidal brackish marshes and streams (males) or freshwater streams (females) to mature. This 20-incher probably attempted to ascend the Susquehanna as an elver in 2016 or 2017. After hitching a ride with some friendly folks, she bypassed the three largest dams on the lower Susquehanna (Conowingo, Holtwood, and Safe Harbor) and arrived in the Conewago where she may remain and grow for ten years or more. To spawn, a perilous and terminally fatal journey to the Sargasso Sea awaits her. (You may better know the area of the Sargasso Sea as The Bermuda Triangle…a perilous place to travel indeed!)
SOURCES
Normandeau Associates, Inc. and Gomez and Sullivan. 2018. Muddy Run Pumped Storage Project Conowingo Eel Collection Facility FERC Project 2355. Prepared for Exelon.
Stambaugh, Jr., John W., and Robert P. Denoncourt. 1974. A Preliminary Report on the Conewago Creek Faunal Survey, Lancaster County, Pennsylvania. Proceedings of the Pennsylvania Academy of Sciences. 48: 55-60.
One can get a stiff neck looking up at the flurry of bird activity in the treetops at this time of year. Many of the Neotropical migrants favor rich forests as daytime resting sites after flying through the night. For others, these forests are a destination where they will nest and raise their young.
The Veery (Catharus fuscescens) is a Neotropical thrush that breeds in extensive mature forest on the dampest slopes of the Diabase ridges in the Gettysburg Basin. Their rolling flute-like songs echo through the understory as newly arrived birds establish nesting territories.
The whistled song of the Baltimore Oriole is often heard long before this colorful Neotropical is seen among the foliage of a treetop. Some dead branches allow us a glimpse of this curious beauty.
The “Pee-a-wee……..Pee-urr” song of the Eastern Wood-Pewee (Contopus virens), a small flycatcher, is presently heard in the Riparian Woodlands at Conewago Falls. It breeds in forested tracts throughout the lower Susquehanna valley. The vocalizations often continue through the summer, ending only when the birds depart to return to the tropics for the winter.
While constructing a nest beneath a tree canopy, an Eastern Wood-Pewee form-fits the cup where eggs will soon be laid.
The Yellow-billed Cuckoo (Coccyzus americana) nests in the treetops of Riparian Woodlands along the Susquehanna and its tributaries. Most arrive during the second half of May for their summer stay. It is a renowned consumer of caterpillars.
The Cedar Waxwing is a notorious wanderer. Though not a Neotropical migrant, it is a very late nester. Flocks may continue moving for another month before pairs settle on a place to raise young.
Of the more than twenty species of warblers which regularly migrate through the lower Susquehanna Valley, the Common Yellowthroat (Geothlypis trichas) is among those which breeds here. It is particularly fond of streamside thickets.
For the birds that arrive earlier in spring than the Neotropical migrants, the breeding season is well underway. The wet weather may be impacting the success of the early nests.
Northern Rough-winged Swallows arrived back in April. At traditional nest sites, including the York Haven Dam and local creek bridges, small groups of adults were seen actively feeding and at times perching in dead treetops during recent days. There was an absence of visits to the actual nest cavities where they should be feeding and fledging young by now. It’s very possible that these nests failed due to the wet weather and flooding. Another nest attempt may follow if drier conditions allow stream levels to subside and there is an increase in the mass of flying insects available for the adults to feed to their young..
A Carolina Chickadee, a resident species, is seen atop a hollow stump where it and a mate are constructing a new nest for a second brood. Did the first brood fail? Not sure.
Common Mergansers are an uncommon but regular nesting species of waterfowl on the lower Susquehanna River. They nest in cavities, requiring very large trees to accommodate their needs. It was therefore encouraging to see this pair on a forested stream in northern Lancaster County during the weekend. However, a little while after this photograph was taken the pair flew away, indicating that they are not caring for young which by now should be out of the nest and on the move under the watchful care of the female.
So long for now, if you’ll excuse me please, I have a sore neck to tend to.
In the event you found yourself missing the spectacle of the migration of Neotropical birds through the northeastern United States earlier this month, there is good news. Apparently the cool and wet weather has prolonged the spring flights which by now are normally slowing to a trickle. Take a look at this composite radar loop and see the masses of birds rising skyward as nightfall progresses from east to west during the past couple of hours.
Nocturnal migrating birds are indicated as they ascend into the path of sweeping radar beams at sites throughout the eastern United States. The outer bands of Tropical Storm Alberto appear over southern Florida and strong thunderstorms are widespread elsewhere. (NOAA/National Weather Service image)
A zoomed-in view of Texas shows a number of items of interest. A tornado warning was issued for the thunderstorm seen north of San Antonio (hook-shaped red in lower center). In the earliest frames of this loop, two well-defined rings expand around radar sites west of San Antonio, followed by a partial ring in the city and another to the north near the thunderstorm. These rings plot accurately with the locations of large bat roosts. The bats, millions of them, ascend high enough to be detected by radar as they depart their roosts to feed at dusk. Finally at nightfall, great masses of Neotropical birds are displayed as they rise into the busy flyway used by northbound migrants after crossing the Rio Grande from Mexico. (NOAA/National Weather Service image)
Any of the birds presently moving through Texas could travel for another week or more to reach the Susquehanna region—so there’s still time to see the show. Let’s grab a camera or some binoculars and go have a look. It’s not too late.
The warm weather late last week and the several inches of rain that followed have left the farm fields of the lower Susquehanna valley a soggy muddy mess…waterlogged. Runoff has made its way down the tributaries to raise the waters of the river and fill up its banks.
Migrating gulls find it difficult to locate food when the Susquehanna becomes a silty turbid torrent. It’s not at all unusual to find hundreds of them enjoying a feast of earthworms in the agricultural uplands when conditions such as these exist. As you may have guessed, the birds alluded to are the familiar Ring-billed Gulls, the same species seen mooching french fries and other snacks in fast-food restaurant parking lots. They are by far the most common inland gull in eastern North America.
A flock of gulls feeding in farmland in the Gettysburg Basin northeast of Conewago Falls. Gulls frequently feed in wet farm fields where earthworms are the prized meal.
Ring-billed Gulls are notorious for loafing and feeding in flocks which seldom include other species of gulls. They are frequently the smallest gull found in their inland habitats, so it is understandable that they may avoid the company of the larger and often more aggressive species.
However, today I was reminded that one must be ever vigilant and check for other species among those flocks presumed to consist solely of Ring-billed Gulls, particularly during times when the river is so inhospitable to passing migrants.
A few Ring-billed Gulls can be seen in this flock consisting almost entirely of noticeably smaller Bonaparte’s Gulls.
Bonaparte’s Gulls are easily recognized by their small size, black heads, and flashy white primary feathers in the wings. They are the only small gull commonly found in the Mid-Atlantic states.
Two Ring-billed Gulls (upper left and upper center) are outflanked by Bonaparte’s Gulls. Bonaparte’s Gulls spend the winter feeding in the surf along the Atlantic coast. As spring migrants they peak in April, closely following the Susquehanna River as they journey through the area. The adults will continue to the northwest, passing through the Great Lakes region to nesting areas in Canada.
Adult Bonaparte’s Gulls in breeding (alternate) plumage have conspicuous black heads.
Several first-year Bonaparte’s Gulls in basic plumage can found among the adults in this image. Most notable is the one to the right of center (flying left). Note its lack of flashy white in the primary feathers of the wings, a black tail bar, and the dark spot behind the eye instead of a black hood. The black spot behind the eye is characteristic of all Bonaparte’s Gulls in basic (non-breeding) plumage, including adults. Bonaparte’s Gulls mature in two years.
Bonaparte’s Gulls invade the farmlands of the Gettysburg Basin. Despite their common name, they seem uninterested in french fries and similar cuisine.
It seems as though the birds have grown impatient for typical spring weather to arrive. The increase in hours of daylight has signaled them that breeding time is here. No further delays can be entertained. They’ve got a schedule to keep.
Thursday, March 29: Winds began blowing from the southwest, breaking a cold spell which had persisted since last week’s snowfall. Birds were on the move ahead of an approaching rainy cold front.
Friday, March 30: Temperatures reached 60 degrees at last. Birds were again moving north through the day, despite rain showers and a change in wind direction—from the northwest and cooler following the passage of the front in the late morning.
Flocks of Double-crested Cormorants followed the Susquehanna River north in numerous V-shaped flocks during the recent several days.
There were Turkey Vultures by the hundreds on the way north.
And nearly as many Black Vultures too.
Saturday, March 31: It was cooler, but birds were still on the wing headed north.
At sunrise, a migrating Northern Flicker stopped by at a suet feeder to refuel.
Osprey pairs have arrived at nest sites on the lower Susquehanna.
Sunday, April 1: The morning was pleasant, but conditions became cooler and breezy in the afternoon. Migratory and resident birds began feeding ahead of another storm.
A distant flock of fast-flying Bonaparte’s Gulls (Chroicocephalus philadelphia) moves expeditiously up the Susquehanna at Conewago Falls as winds begin to pick up during the late morning. Are they hurrying to get north of the path of the forthcoming weather system?
A Mourning Dove (Zenaida macroura) feeds in anticipation of a snowy night ahead.
A male Downy Woodpecker devours a late-afternoon meal.
This Tufted Titmouse (Baeolophus bicolor), a cavity-nesting species, is distracted by a potential new home.
Dark-eyed Juncos winter in the lower Susquehanna valley. During the month of April, they will begin departing for their breeding grounds, some nesting in the mountains just to our north.
Tufted Titmouse…still house hunting.
A male American Goldfinch is progressing through molt into a showy breeding (alternate) plumage.
A male House Finch takes a break from its melodious song to feed before the arrival of our next spring snow. His mate is already incubating eggs in a nest not far away.
Northern Cardinals (Cardinalis cardinalis) feed through the late afternoon, often as the last birds out-and-about before darkness. This male remains close to his mate as she forages beneath nearby shrubs.
Monday, April 2: Snow fell again, overnight and through the morning—a couple of inches. Most of the snow had melted away by late afternoon.
Horned Larks are plentiful in large open bare-soil (tilled) farmlands in winter, particularly near fresh manure. Their sandy-tan coloration hides them well, and they are seldom noticed unless spotted at roadside following snow storms. Horned Larks are migratory ground-nesting birds found in many sparsely vegetated habitats including tundra, parched fields and prairies, beaches, and even airports. There is a breeding population in the lower Susquehanna valley which may be increasingly attracted to favorable nesting habitat created in some no-till fields, possibly using a window of opportunity between the demise of cold-season cover crops and the ascendency of the warm-season crops to complete a brood cycle. Comparing the site selection and success rates of nesting Horned Larks under various crop management methods, including reactions to herbicide use, could be an enlightening study project for inquisitive minds. (Hint-Hint)
The dainty Chipping Sparrow has arrived. This species commonly nests in small trees, often in suburban gardens.
“Fear is the darkroom where negatives are developed.”
—Anonymous
I celebrate alone, entering my fortieth year of fame. Everyone knows me; they’ve all heard my name. The world won’t recognize Berwick, Salem, Peach Bottom, or the place near Springfield (not the one with the donut-eating man who drools when he sleeps on the job, the real one in Montgomery County, Pennsylvania). Oyster Creek, Beaver Valley, Hope Creek, and dozens of others won’t ring a bell, but they’ll recall me with emotion or story, and often with myth as well—I’m a Nuclear Star.
I’m the ultimate thriller, generating anxiety from day one. My worldwide debut was the stuff of legend; you saw me on the news. You remember all the dramatic tension, don’t you? Like all celebrities, I blew off a little steam, had a little gas, and then everyone waited, trying to figure out what was going to happen next. But I kept things under wraps, shrouded in a fog of mystery, not a sole eyewitness to the events in my inner sanctum. Confusion reigned. There was a sense of great danger and imminent catastrophe. There prevailed a sweaty uncertainty over the threat of disaster and invisible death.
Would I melt down?
Would I blow my top?
Those iconic and sinister towers, what kind of horrid poisons pour from them to burn the sky and land?
The world needed to know. People demanded information.
Well, I know your trust in me was eroded and you felt deceived by my agents. You saw it, how they withered in the spotlight of fame while trying to protect themselves and the new Nuclear Star. The uncertainty they caused motivated many of my neighbors to leave. Many more were pushed beyond rational skepticism about me to an enduring cynicism which persists to this day. Fortunately, a genuine, competent, straight-talking communicator arrived to allay everyone’s fears with frank and understandable explanations of the situation. Then, a visit by the President of the United States assuaged the trepidations of a frightened public and provided reassurance to those who left that it was safe to return.
I want everyone to know that I had plans for a long quiet career. Then, three months into it, a handler pressed my buttons the wrong way and I’ve been in the limelight ever since. I did melt down a bit, but thanks to a timely intervention, I didn’t drop through the floor. For the same reason, I didn’t go through the roof either. You need to know that I’m no bomb. I was built to last for the long haul, and I won’t go to pieces. Remember, I’m a Nuclear Star. Oh, and those really are just big fluffy white steam clouds coming out of those towers, nothing more. It’s true.
I’m really not so scary. There’s no scheming evil little man hiding in my shadow planning the demise of the planet. Only the flies sit around rubbing their tiny hands together as they contemplate their next move, and I’ll remind you that not even one of them was hurt here.
I’m a Nuclear Star; my legacy is secured. Come look at me and feel the awe. After all these years, I continue to make nervous those who see me in person. You’ll still see the crowds and cameras outside my gates from time to time, demanding to know what kind of devious scheme is being hatched inside. I remain a central figure, but typecast as the villain. Without fail, I’m presumed to be the deleterious factor when man or nature ails. It’s not the coal-choker down the river, or the dam wall next door. It’s not the smoldering trash cookers north and south, or the sludge on the fields. It’s not the junk mixed into the food, or the spraying willy-nilly. Nor is it the filth in the water, the lazy life, or the smog in the city. It’s not the cigarette in your mouth, the synthetics in your house, the hours in your car. It’s Three Mile Island. That’s what did it. I’m a Nuclear Star.
Three Mile Island Nuclear Generating Station. Unit 2 (left) has been shut down since the March 28, 1979 accident and partial meltdown. Unit 1 (right) is currently operating and producing electricity.
Oh, and by the way, the plant in Montgomery County is called Limerick, in case you were wondering.
Snow accumulations from yesterday’s storm amounted to approximately 12 inches in the vicinity of Conewago Falls, some areas of the lower Susquehanna valley receiving more.
American Robins were in the process of moving north through the region in abundance just prior to the arrival of our latest “nor’easter”. When the storm struck in the early morning hours yesterday, their flights were grounded. After sunrise this morning, hungry robins quickly seized the opportunity to feed using the only open ground available—the edges of cleared roadways, particularly where they pass through woodlots and agricultural lands. Other migrants use the same strategy, picking and probing the wet soils alongside quickly thawing pavement to search for morsels of sustenance.
Early this morning, an American Robin takes a break from tossing the soil to search for invertebrates along the roadside edge of a snow-covered farm field.
Nearly all of the robins seen today were males, indicating that the migration is still in its early stages with the females yet to come.
A Killdeer feeds on the muddy edge of a thoroughfare bisecting snowy cropland.
This American Robin is one of dozens seen feeding on the steep south-facing slope of a road cut excavated through Gettysburg Formation redbeds. This little sun-drenched oasis along a sparsely traveled rural road was snow-free by early afternoon, much to the delight of feathered travelers whose weather-induced stopovers will soon come to an end. The journey will continue.
You remember the signs of an early spring, don’t you? It was a mild, almost balmy, February. The earliest of the spring migrants such as robins and blackbirds were moving north through the Lower Susquehanna River Watershed. The snow had melted and ice on the river had passed. Everyone was outdoors once again. At last, winter was over and only the warmer months lie ahead…beginning with March.
Common Grackles are often the first perching birds to begin moving north through the lower Susquehanna valley in spring. They often winter in large roving flocks of mixed blackbird species on the nearby Atlantic Coastal Plain Province. These flocks sometimes wander the farmlands of the lower Piedmont Province near the river, but rarely stray north of the 40th parallel before February.
Ah yes, March, the cold windy month of March. We remember February fondly, but this March has startled us out of our vernal daydreams to wrestle with the reality of the season. And if you’re anywhere near the Mid-Atlantic states on this first full day of spring, you know that a long winter’s nap and visions of sugar peas would be time better spent than a stroll outdoors. Presently it’s dusk, and the snow from the 4th “Nor’easter” in a month is a foot deep and still falling.
In honor of “The Spring That Was”, here then is a sampling of some of the migratory waterfowl that have found their way to the Lower Susquehanna River Watershed during March. Some are probably lingering and feeding for a while. All will move along to their breeding grounds within a couple of weeks, regardless of the weather.
Tundra Swans will migrate in a northwest direction to reach breeding grounds west and north of Hudson Bay.
Migratory Canada Geese departing the Chesapeake Bay area typically pass over the lower Susquehanna valley at high altitudes. A south wind can bring a sustained day-long flight of migrating geese and ducks over the region on a given day in late-February or March.
Snow Geese (Chen caerulescens) historically wintered in the marshes of the Atlantic seaboard where the tide cycle kept vegetation primarily snow-free for feeding. Removal of hedgerows and intensive farming since the 1980s has attracted these birds to inland agricultural lands during their preparation for the move north. For nearly three decades, tens of thousands have annually begun their spring journey with a stopover at the Middle Creek Wildlife Management Area. Flocks range widely from Middle Creek to feed, commonly as far west as the fields of the Conewago Creek valley in the Gettysburg Basin to the east of Conewago Falls.
American Black Ducks
A pair of Northern Shovelers (Anas clypeata).
Ring-necked Ducks (Aythya collaris) are “diving ducks”.
A male Lesser Scaup, Aythya affinis, (front center) and Ring-necked Ducks (rear and left) seen between feeding dives.
A male Bufflehead (Bucephala albeola). These miniature diving ducks will sometimes winter on the Susquehanna in “rafts” of dozens of birds.
Tundra Swans journey toward the “Land of the Mid-Night Sun”.
Many are wont to say that they have no capacity for scientific pursuits, and having no capacity, they consequently have no love for them. I do not believe, that as a general thing, a love for science is necessarily innate in any man. It is the subject of cultivation and is therefore acquired. There are doubtless many, whose love for these and kindred pursuits is hereditary, through the mental biases and preoccupations of their progenitors, but in the masses of mankind it is quite otherwise. In this consists its redeeming qualities, for I do not think the truly scientific mind can either be an idle, a disorderly, or a very wicked one. There may be scientific men, who, forgetful of its teachings, are imperious and ambitious–who may have foregone their fealty to their country and their God, but as a general thing they are humble, social and law-abiding. If, therefore, there is a human being who desires to break off from old and evil associations, and form new and more virtuous ones, I would advise him to turn his attention to some scientific specialty, for the cultivation of a new affection, if there are no other and higher influences more accessible. In this pursuit he will, in time, be enabled to supplant the old and heartfelt affection. The occupation of his mind in the pursuit of scientific lore will wean him from vicious, trivial, and unmanly pursuits, and point out to him a way that is pleasant and instructive to walk in, which will ultimately lead to moral and intellectual usefulness. I wish I was accessible to them, and possessed the ability to impress this truth with sufficient emphasis upon the minds of the rising generation. This fact, that in all moral reformations, a love for the opposite of any besetting evil must be cultivated, before that evil can be surely eradicated, has been too much overlooked and too little valued in moral ethics. But true progress in this direction implies that, under all circumstances, men should “act in freedom according to reason.”
-Simon S. Rathvon
In the cellar of the North Museum on the campus of Franklin and Marshall College in Lancaster, Pennsylvania, is an assemblage of natural history specimens of great antiquity. The core of the collection has its origins in the endeavors of a group of mid-to-late nineteenth-century naturalists whose diligence provided a most thorough study of the plants and animals found within what was at the time America’s most productive farming county.
The members of the Linnaean Society of Lancaster City and County shared a passion for collecting, identifying, classifying, and documenting the flora and fauna of the region. Some members were formally educated and earned a living in the field of science, but the majority were in the process of self-education and balanced their natural history occupation with an unrelated means to provide financially for their families. The latter benefited greatly from their associations with the former, gaining expertise and knowledge while participating in the functions of the group.
On February 24, 1866, Simon S. Rathvon, the society’s Treasurer, read an essay in commemoration of the group’s fourth anniversary. Rathvon earned a living as a tailor, first in Marietta, a thriving river town at the time, then in Lancaster City. In 1840, Rathvon was elected into the Marietta Natural History Lyceum where, as a collections curator, he became associated with principals Judge John J. Libhart, an amateur ornithologist, and Samuel S. Haldeman, a geologist and soon to be widely-known malacologist. Haldeman, in 1842, upon noticing the new member’s interest in beetles and other insects, provided books, guidance, and inspiration, thus intensifying Rathvon’s study of entomology. Rathvon’s steadfast dedication eventually led to his numerous achievements in the field which included the publication of over 30 papers, many on the topic of agricultural entomology. Rathvon’s scientific understanding of insect identification and taxonomy was a foundation for his practical entomology, which moved beyond mere insect collection to focus upon the study of the life histories of insects, particularly the good and bad things they do. He then applied that knowledge to help growers solve pest problems, often stressing the value of beneficial species for maintaining a balance in nature. From 1869 through 1884, Rathvon edited and published Lancaster Farmer, a monthly (quarterly from 1874) agricultural journal in which he educated patrons with his articles on “economic entomology”. Rathvon continued earning a living in the tailor business, seemingly frustrated that his financially prudent advice on insect control in Lancaster Farmer failed to entice more would-be readers to part with the one dollar annual subscription fee. For many years, Rathvon crafted articles for local newspapers and wrote reports for the United States Department of Agriculture. In recognition of his achievements, Simon Rathvon received an honorary Ph.D. from Franklin and Marshall College in 1878.
In Rathvon’s anniversary essay, he details the origins of the Linnaean Society as a natural science committee within the “Lancaster Historical, Mechanical, and Horticultural Society” founded in 1853. The members of the committee, not finding sufficient support within the parent organization for their desired mission, “the cultivation and investigation of the natural history of Lancaster County…”, sought to form an independent natural history society. In February of 1862, the “Linnaean Society of Lancaster City and County” was founded to fulfill these ambitions.
Above all else, the written works by the members of the Linnaean Society and their predecessors have provided us with detailed accounts of the plants and animals found in Lancaster County, and in the lower Susquehanna River valley, using scientific binomial nomenclature, a genus and species name, as opposed to the variable folk and common names which, when used exclusively, often confuse or mislead readers. Consider the number of common names a species could have if just one was assigned by each of the languages of the world. Binomial nomenclature assigns one designation, a genus name and species name, in Latin, to each life-form (such as Homo sapiens for Humans), and it is adopted universally.
Rathvon would say of the naming of the Linnaean Society:
“…the name which the Society has adopted is in honorable commemoration of LINNAEUS, the great Swedish naturalist—one who may be justly regarded as a father in Natural Science. To him belongs the honor of having first promulgated the “binomial system of nomenclature,” a system that has done more to simplify the study of natural science than any light that has been brought to the subject by any man in any age.”
Carl Linnaeus lived from 1707 to 1778, and published his first edition of Systema Naturae in 1735.
The names of a number of the members and corresponding members on the Linnaean Society of Lancaster City and County’s rolls remain familiar. John P. McCaskey (educator) served as Corresponding Secretary. Doctor Abram P. Garber was a prominent Lancaster botanist and society member. Professor Samuel S. Haldeman (naturalist, geologist, and philologist), Professor J. L. LeConte (entomologist), Judge John J. Libhart, Professor Asa Gray (botanist), and the foremost legal egalitarian in the United States House of Representatives, the Honorable Thaddeus Stevens, were listed among the roster of corresponding members.
By the end of its fourth year, Rathvon enumerated the specimens in the collections of the society to exceed 32,000. These included all the species of mosses and plants known in the county, 200 bird specimens, an enormous insect collection with nearly 12,000 Coleoptera (Beetles), and more than 1,400 mollusk shells. The work of the society had already provided a thorough baseline of the flora and fauna of the lower Susquehanna River valley and Lancaster County.
Rathvon would continue as Treasurer and primary curator through the group’s first twenty-five years, their most active. By 1887, their library contained over 1,000 volumes, they possessed over 40,000 specimens, and more than 600 scientific papers had been read at their meetings.
Many of the society’s specimens were moved to the custody of Franklin and Marshall College following the group’s dissolution. In 1953, the collection found a home on the F&M campus at the newly constructed North Museum, named for benefactor Hugh M. North, where many of the specimens, particularly the birds, are on prominent display.
Among the mounted specimens in the North Museum collection is a Heath Hen, once a numerous coastal plain bird which was also of limited abundance in the Piedmont Province areas of southeast Pennsylvania prior to its rapid decline during the first half of the nineteenth century. In southern Lancaster County, the burned grasslands of the serpentine barrens in Fulton Township may have provided suitable Heath Hen habitat prior to the bird’s demise. Curiously, Judge John J. Libhart did not note the Heath Hen in his enumeration of the birds of Lancaster County in either 1844 or 1869, indicating it was seriously imperiled or may have already been extirpated.
The Heath Hen (Tympanuchus cupido cupido) became extinct in 1932. While the collection of this particular specimen had little significant impact on the population of this subspecies as a whole, prolonged hunting pressure was largely responsible for decimating the numbers of Heath Hens on the mainland of the Atlantic Coastal Plain. According to the museum tag, this specimen was “probably taken in southern Lancaster County prior to 1850”, and was part of the collection belonging to the Linnaean Society of Lancaster City and County. It is among hundreds of bird specimens on display in antique wood and glass cabinets in the North Museum.
The Heath Hen was extirpated from its entire Atlantic Coastal Plain mainland range by the mid-1860s. The last remaining population was restricted to Martha’s Vineyard where, for the first time, a conservation effort was initiated to try to save a species. After some promising rebounds, the Heath Hen’s recovery failed for a variety of reasons including: the population’s isolation on an island, severe winter storms, feral cat predation, and a flawed understanding of methods for conducting mosaic burns to maintain the bird’s scrub habitat and prevent large catastrophic fires. A large fire in 1906 reduced the island population to just 80 birds, then there was a strong rebound to an estimated 2,000 birds (800 counted) by April, 1916. One month later, a fire burned twenty percent of Martha’s Vineyard, striking while females were on the nest, and leaving mostly males as survivors. A downward spiral in numbers followed for another decade. Finally, from 1929 until his death in 1932, “Booming Ben”, the last Heath Hen, searched the island every spring for a mate that wasn’t there.
Based on life history and the morphology of specimens, the Heath Hen has long been considered to be a subspecies of the Greater Prairie Chicken (Tympanuchus cupido pinnatus), a bird of the tallgrass prairies. However, for more than a decade now, modern DNA analysis has kept taxonomists busy reclassifying and reworking the “tree of life”. For certain species, genetic discoveries often disqualify the long-trusted practice of determining a binomial name based on the visual appearance of specimens. Molecular study is making Linnaean classification more scientific, and is gradually untangling a web of names that man has been weaving for 200 years, often with scant evidence, in an effort to better understand the world around him. In the case of the Heath Hen, DNA research has thus far failed to conclusively determine its relationship to other species of prairie chickens. The lack of a sufficient pool of genetic material, particularly from mainland Heath Hens, reduces the ability of researchers to draw conclusions on this group of birds. There remains the possibility that the Heath Hen was genetically distinct from the Greater Prairie Chickens of the mid-western United States. This would be bad news for organizations studying the possibility of introducing the latter into the former’s historic range as a restoration program.
The Carolina Parakeet (Conuropsis carolinensis) specimen on display at the North Museum was collected by John C. Jenkins in Nanchez, Mississippi in 1835. The specimen was remounted by conservator H. Justin Roddy.
The last Carolina Parakeet (the only parrot species native to the eastern United States) died in captivity in the Cincinnati Zoo on February 21, 1918, one hundred years ago this past week. It was a species inhabiting primarily the lowland forests of the southeastern United States
In Lancaster County, Judge John J. Libhart wrote of the species in 1869, “…Carolina Parrot, Accidental; a flock seen near Manheim by Mr. G. W. Hensel.” Libhart did not mention the species in his earlier ornithological writings (1844). Therefore, the Hensel sighting probably occurred sometime between 1844 and 1869. The fate of a specimen reported to have been collected in the town of Willow Street sometime during the nineteenth century is unknown, the written details lack the date of its origin and other particulars that may clarify the authenticity of the sighting.
McKinley (1979) researched numerous historical sight records of Carolina Parakeets, but found no specimen from Lancaster County, or from Pennsylvania, New Jersey, Delaware, the District of Columbia, or Maryland to substantiate any of the reports in the Mid-Atlantic states. In the days prior to high-speed photography, verification and documentation of the presence of an animal species relied on what seems today to be a brutal and excessive method of nature study, killing. Lacking a specimen, the historical status of Carolina Parakeets in Pennsylvania, an area often considered to be within the bird’s former range, may be considered by many authorities to be hypothetical.
The Passenger Pigeon (Ectopistes migratorius) was abundant in the lower Susquehanna River valley through the early nineteenth century. Specimens in the North Museum collection include colorful males in breeding plumage. Several are from the original Linnaean Society of Lancaster City and County collection.
The Passenger Pigeon, too, has been extinct for more than a century. In Lancaster County, Judge John J. Libhart listed the Passenger Pigeon by the common name “Wild Pigeon” and wrote of the species in 1869, “Migratory; spring and autumn; feeds on grain, oak and beach, mostly on berries; stragglers sometimes remain and breed in the county.” There are numerous accounts of their precipitous decline both locally and throughout their former range, each illustrating the tragic loss of another portion of the North American natural legacy.
The North Museum specimen label describes the precipitous decline of the Passenger Pigeon in the lower Susquehanna River valley.
Martha, the last surviving Passenger Pigeon, died on September 1, 1914, in the Cincinnati Zoo. Ironically, the last Carolina Parakeet would die in the same enclosure just three-and-one-half years later. In the wild, the final three records of Passenger Pigeons were all of birds that were shot for taxidermy mounts in 1900, 1901, and 1902—an embarrassing human legacy.
By the early twentieth century, concerned citizens were beginning to realize the danger posed to many species of flora and fauna by man’s activities. In the eastern United States, the vast forests had been logged, the wetlands drained, and the streams and rivers dammed. Nearly all of the landscape had been altered in some way. Animals were harvested with little concern for the sustenance of their populations. Nearly unnoticed, the seemingly endless abundance and diversity of wildlife found in the early days of European colonization had dwindled critically.
In 1844, Judge John J. Libhart noted the “Log-Cock” among the birds found in Lancaster County. Fortunately, he included the scientific name “Picus pileatus”, the binomial nomenclature then recognized for the Pileated Woodpecker (specimens to right) among taxonomists. A record of “Log-Cock” could confuse researchers, leaving them to guess whether Libhart was referring to a woodpecker, a woodcock, a grouse, or any number of other birds including the long-extinct(?) Ivory-billed Woodpecker (Campephilus principalis). Of the Pileated Woodpecker (Dryocopus pileatus today), Libhart wrote in 1869, “…now become rare and is only met with in old and extensive woods; breeds in the county.” The Ivory-billed Woodpecker (specimen to left), a species of vast forests of large timber, living and dead, was restricted to the southeastern United States and Cuba. Logging following the American Civil War and, to a lesser degree, shooting impacted both species detrimentally. The Pileated Woodpecker recovered, the larger Ivory-billed Woodpecker, which has never been documented in the northeastern United States, has not. These specimens are in the North Museum collection.
The movement to conserve and protect threatened species from relentless persecution owes its start to the Linnaean taxonomists, the specimen collectors who gave uniformly recognizable names to nearly all of North America’s plants and animals. Significant too were John James Audubon and many others who used specimens as models to create accurate artwork which allowed scientists and citizens alike to learn to identify and name the living things they were seeing and, as time went by, not seeing.
Binomial nomenclature enabled the new conservationists to communicate accurately, reducing misunderstandings resulting from the use of many different names for one species or a shared name for multiple species. Discussions on the status of Columba migratorius (the binomial name for Passenger Pigeon in the nineteenth century) could occur without using the confusing local names for the Passenger Pigeon such as Wood Pigeon or, here in Pennsylvania, Wild Pigeon, a term which could describe any number of free-ranging pigeon or dove species. A binomial name, genus and species, makes the identity of a particular plant or animal, for lack of a more fitting term, specific.
Appreciation for the work completed by taxonomists who killed thousands of animals so each could be classified and assigned a name particular to its lineage is what finally motivated some to seek a cessation of the unchecked catastrophic killing of living things. It’s the paradox of late nineteenth-century conservation. The combined realization that a species is unique among other life-forms and that continuing to kill it for specimens, “style”, “sport”, or just an adrenaline thrill could eliminate it forever became an intolerable revelation. The blood would be on the hands of an audacious mankind, and it was unthinkable. Something had to be done. Unfortunately for the Passenger Pigeon, the Carolina Parakeet, and the Heath Hen, help came too late.
SOURCES
Greenburg, Joel. 2014. A Feathered River Across the Sky: The Passenger Pigeon’s Flight to Extinction. Bloomsbury Publishing. New York.
Libhart, John J. 1844. “Birds of Lancaster County”. I. Daniel Rupp’s History of Lancaster County. Gilbert Hills. Lancaster, PA.
Libhart, John J. 1869. “Ornithology”. J. I. Mombert’s An Authentic History of Lancaster County. J. E. Barr and Company. Lancaster, PA.
McKinley, Daniel. 1979. “History of the Carolina Parakeet in Pennsylvania, New Jersey, Delaware, Maryland, and the District of Columbia”. Maryland Birdlife. 35(1):1-10.
Palkovacs, Eric P.; Oppenheimer, Adam J.; Gladyshev, Eugene; Toepfer, John E.; Amato, George; Chase, Thomas; Caccone, Adalgesia. 2004. “Genetic Evaluation of a Proposed Introduction: The Case of the Greater Prairie Chicken and the Extinct Heath Hen”. Molecular Ecology. 13(7):1759-1769.
Rathvon, S. S. 1866. An Essay on the Origin of the Linnaean Society of Lancaster City and County, Its Objects and Progress. Pearsol and Geist. Lancaster, Pennsylvania.
Wheeler, Alfred G., Jr. and Miller, Gary L. 2006. “Simon Snyder Rathvon: Popularizer of Agricultural Entomology in Mid-19th Century America”. American Entomologist. 52(1):36-47.
Winpenny, Thomas R. 1990. “The Triumphs and Anguish of a Self-Made Man: 19th Century Naturalist S. S. Rathvon”. Pennsylvania History. 57(2):136-149.
At the moment there is a heavy snow falling, not an unusual occurrence for mid-February, nevertheless, it is a change in weather. Forty-eight hours ago we were in the midst of a steady rain and temperatures were in the sixties. The snow and ice had melted away and a touch of spring was in the air.
Big Bluestem in the Riverine Grasslands is inundated by the rising waters of the Susquehanna at Conewago Falls. The river ice has been dispersed by the recent mild temperatures and rains.
Anyone casually looking about while outdoors during these last several days may have noticed that birds are indeed beginning to migrate north in the lower Susquehanna valley. Killdeer, American Robins, Eastern Bluebirds, Red-winged Blackbirds, and Common Grackles are easily seen or heard in most of the area now.
Just hours ago, between nine o’clock this morning and one o’clock this afternoon, there was a spectacular flight of birds following the river north, their spring migration well underway. In the blue skies above Conewago Falls, a steady parade of Ring-billed Gulls was utilizing thermals and riding a tailwind from the south-southeast to cruise high overhead on a course toward their breeding range.
Ring-billed Gulls swarm in a thermal updraft above Conewago Falls to gain altitude prior to streaming off to the north and continuing their journey.
Ring-billed Gulls climbing to heights sometimes exceeding 1,000 feet before breaking off and gliding away to the north.
The swirling hoards of Ring-billed Gulls attracted other migrants to take advantage of the thermals and glide paths on the breeze. Right among them were 44 Herring Gulls, 3 Great Black-backed Gulls, 12 Tundra Swans (Cygnuscolumbianus), 10 Canada Geese, 3 Northern Pintails (Anas acuta), 6 Common Mergansers, 3 Red-tailed Hawks, a Red-shouldered Hawk, 6 Bald Eagles (non-adults), 8 Black Vultures, and 5 Turkey Vultures.
A first-year Herring Gull (top center) is a standout in a “kettle” of Ring-billed Gulls.
How many Ring-billed Gulls passed by today? More than 18,000…with emphasis on MORE THAN. You see, early this afternoon, the handy-dandy clicker-counter used to tick off and tally the big flights of birds as they pass by quit clicking and counting. Therefore, 18,000 is the absolute minimum number of Ring-billed Gulls seen migrating north today. Hopefully the trusty old oil can will get the clicker working again soon.
In the afternoon, the clouds closed in quickly, the flight ended, and by dusk more than an inch of snow was on the ground. Looks like spring to me.
Two days ago, widespread rain fell intermittently through the day and steadily into the night in the Susquehanna drainage basin. The temperature was sixty degrees, climbing out of a three-week-long spell of sub-freezing cold in a dramatic way. Above the ice-covered river, a very localized fog swirled in the southerly breezes.
By yesterday, the rain had ended as light snow and a stiff wind from the northwest brought sub-freezing air back to the region. Though less than an inch of rain fell during this event, much of it drained to waterways from frozen or saturated ground. Streams throughout the watershed are being pushed clear of ice as minor flooding lifts and breaks the solid sheets into floating chunks.
Today, as their high flows recede, the smaller creeks and runs are beginning to freeze once again. On larger streams, ice is still exiting with the cresting flows and entering the rising river.
Ice chunks on Swatara Creek merge into a dense flow of ice on the river in the distance. Swatara Creek is the largest tributary to enter the Susquehanna in the Gettysburg Basin. The risk of an ice jam impounding the Swatara here at its mouth is lessened because rising water on the river has lifted and broken the ice pack to keep it moving without serious impingement by submerged obstacles. Immovable ice jams on the river can easily block the outflow from tributaries, resulting in catastrophic flooding along these streams.
Fast-moving flows of jagged ice race toward Three Mile Island and Conewago Falls. The rising water began relieving the compression of ice along the shoreline during the mid-morning. Here on the river just downstream of the mouth of Swatara Creek, ice-free openings allowed near-shore piles to separate and begin floating away after 10:30 A.M. E.S.T. Moving masses of ice created loud rumbles, sounding like a distant thunderstorm.
Ice being pushed and heaved over the crest of the York Haven Dam at Conewago Falls due to compression and rising water levels.
Enormous chunks of ice being forced up and over the York Haven Dam into Conewago Falls and the Pothole Rocks below.
Ice scours Conewago Falls, as it has for thousands of years.
The action of ice and suspended abrasives has carved the York Haven Diabase boulders and bedrock of Conewago Falls into the amazing Pothole Rocks.
The roaring torrents of ice-choked water will clear some of the woody growth from the Riverine Grasslands of Conewago Falls.
To the right of center in this image, a motorcar-sized chunk of ice tumbles over the dam and crashes into the Pothole Rocks. It was one of thousands of similar tree-and-shrub-clearing projectiles to go through the falls today.
The events of today provide a superb snapshot of how Conewago Falls, particularly the Diabase Pothole Rocks, became such a unique place, thousands of years in the making. Ice and flood events of varying intensity, duration, and composition have sculpted these geomorphologic features and contributed to the creation of the specialized plant and animal communities we find there. Their periodic occurrence is essential to maintaining the uncommon habitats in which these communities thrive.
Fish Crows (Corvus ossifragus) gather along the flooding river shoreline. Soon there’ll be plenty of rubbish to pick through, some carrion maybe, or even a displaced aquatic creature or two to snack upon.
Is this the same Conewago Falls I visited a week ago? Could it really be? Where are all the gulls, the herons, the tiny critters swimming in the potholes, and the leaping fish? Except for a Bald Eagle on a nearby perch, the falls seems inanimate.
Yes, a week of deep freeze has stifled the Susquehanna and much of Conewago Falls. A hike up into the area where the falls churns with great turbulence provided a view of some open water. And a flow of open water is found downstream of the York Haven Dam powerhouse discharge. All else is icing over and freezing solid. The flow of the river pinned beneath is already beginning to heave the flat sheets into piles of jagged ice which accumulate behind obstacles and shallows.
Ice and snow surround a small zone of open water in a high-gradient area of Conewago Falls.
Ice chunks and sheets accumulate atop the York Haven Dam. The weight of miles of ice backed up behind the dam eventually forces the accumulation over the top and into the Pothole Rocks below. The popping and cracking sounds of ice both above and below the dam could be heard throughout the day as hydraulic forces continuously break and move ice sheets.
Steam from the Unit 1 cooling towers at the Three Mile Island Nuclear Generating Station rises above the frozen Riverine Grasslands at Conewago Falls. The scouring action of winter ice keeps the grasslands clear of substantial woody growth and prevents succession into forest.
Despite a lack of activity on the river, mixed flocks of resident and wintering birds, including this White-breasted Nuthatch (Sitta carolinensis), were busy feeding in the Riparian Woodlands. The White-breasted Nuthatch is a cavity nester and year-round denizen of hardwoods, often finding shelter during harsh winter nights in small tree holes.
The White-breasted Nuthatch is often seen working its way head-first down a tree trunk as it probes with its well-adapted bill for insects among the bark.
Jackpot!
Looking upstream from the river’s east shore at ice and snow cover on the Susquehanna above Conewago Falls and the York Haven Dam. The impoundment, known as Lake Frederic, and its numerous islands of the Gettysburg Basin Archipelago were locked in winter’s frosty grip today. Hill Island (Left) and Poplar Island (Center) consist of erosion-resistant York Haven Diabase, as does the ridge on the far shoreline seen rising in the distance between them. To the right of Poplar Island in this image, the river passes by the Harrisburg International Airport. At the weather station there, the high temperature was eighteen degrees Fahrenheit on this first day of 2018.
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A steady stream of birds was on the move this morning over Conewago Falls. There were hundreds of Ring-billed Gulls, scores of Herring Gulls, and a few Great Black-backed Gulls to dominate the flight. Then too there were thirteen Mallards, Turkey Vultures and a Black Vulture, twenty or more American Robins, a half a dozen Bald Eagles (juvenile and immature birds), a couple of Red-winged Blackbirds, and, perhaps most unusual of all, a flock of a dozen Scoters (Melanitta species), a waterfowl typical of the Mid-Atlantic surf in winter. All of these birds were diligently following the river, and into a headwind no less.
“Hold on just a minute there, buster,” you may say, “I’ve looked at the migration count by dutifully clicking on the logo above and there is nothing but zeroes on the count sheet for today. The season totals have not changed since the previous count day!”
Ah-ha, my dedicated friend, correct you are. It seems that today’s bird flight was solely in one direction. And that direction was upriver, moving north into a north breeze, on a heading which conflicts with all logic for creatures that should still be headed south for winter. As a result, none of the birds observed today were counted on the “Autumn Migration Count”.
You might say, “Don’t you know that Winter Solstice was three days ago, so autumn and autumn migration is over.”
Okay, point well taken. I should therefore clarify that what we title as “Autumn Migration Count” is more accurately a census of birds, insects, and other creatures transiting from northerly latitudes to more favorable latitudes to the south for winter. This transit can begin as early as late June and extend into the first weeks of winter. While most of this movement is motivated by the reduced hours of daylight during the period, late season migrants are often responding to ice, bad weather, or lack of food to prompt a journey further south. Migration south in late December and January occurs even while the amount of daylight is increasing slightly in the days following the Winter Solstice.
So what of the birds seen flying north today? There was some snow cover that has melted away, and the ice that formed on the river a week ago is gone due to the milder than normal temperatures this week.
One may ask, “Were the birds seen today migrating north?”
Let’s look at the species seen moving upriver today a try to determine their motivation.
First, and perhaps most straight-forward, is the huge flight of gulls. Wintering gulls on the Susquehanna River near Conewago Falls tend to spend their nights in flocks on the water or on treeless islands and rocky outcrops in the river. Many hundreds, sometimes thousands, find such favorable sites along the fifteen mile stretch of river from Conewago Falls downstream to Lake Clarke and the Conejohela Flats at Washington Boro. Each morning most of these gulls venture out to suburbia, farmland, landfill, hydroelectric dams, and other sections of river in search of food. Gulls are very able fliers and easily cover dozens of miles outbound and inbound each day in search of food. Many of the gulls seen this morning were probably on their way to the Harrisburg metropolitan area to eat trash. Barring any extraordinary buildups of ice on this section of river, one would expect these gulls to remain and make these daily excursions to food sources through early spring.
Ring-billed Gulls fly upriver through the Pothole Rocks at Conewago Falls.
Herring Gulls stream upriver through Conewago Falls on their way to fine dining.
Second, throughout the season Bald Eagles have been tallied on the migration count with caution. Flight altitude, behavior, plumage, and the reaction of the “local” eagles to these transients was carefully considered before counting an eagle as a migrant. They roam a lot, particularly when young, and range widely to feed. The movement of eagles up the river today was probably food related. A gathering of adult, juvenile, and immature Bald Eagles could be seen more than a half mile upstream from the migration count lookout. Those moving up the river seemed to assemble with the “locals” there throughout the morning. White-tailed Deities occasionally drown, particularly when there is thin or unstable ice on the river (as there was last week) and they attempt to tread upon it. Then, their bodies are often stranded among rocks, in trees, or on the crown of the dam. After such a mishap, their carcasses become meals for carrion-eaters in the falls. Such an unfortunate deity, or another source of food, may have been attracting the eagles in numbers today.
A distant gathering of Bald Eagles at the south end of Three Mile Island in upper Conewago Falls.
Next, Black and Turkey Vultures often roam widely in search of food. The small numbers seen headed up-river today would tend to mean very little when trying to determine if there is a trend or population shift. Again, food may have been luring them upriver from nearby roosts.
And finally, the scoters, Mallards, American Robins, and Red-winged Blackbirds may have been wandering as well. Toward mid-day, the wind speed picked up and the direction changed to the east. This raises the possibility that these and others of the birds seen today may sense a change in weather, and may seek to take flight from the inclement conditions. Prompted by the ocean breeze and in an attempt to avoid a storm, was there some movement away from the Atlantic Coastal Plain to the upper Piedmont today? Many species may make these types of reactive movements. Is it possible that some birds flee or avoid ever-changing storm tracks and alter there wintering locations based on jet streams, water currents, and other climatic conditions? Probably. These are interesting dynamics and something worthy of study outside the simpler methods of a migration count.
A Ring-billed Gull begins feeding as storm clouds approach Conewago Falls at mid-day. This and other gull species travel widely in their winter range to find food and safe roosting sites. For them, northward spring migration usually begins no earlier than late February.
…And if it snows that stretch down south won’t ever stand the strain… –Jimmy Webb
The lower Susquehanna valley’s first snowfall of the season arrived yesterday. By this morning it measured just an inch in depth at Conewago Falls, more to the south and east, less to the west and north. By mid-morning a cold fresh to moderate breeze from the northwest was blowing through the falls and stirring up ripples on the river.
Light snow on the Conewago Falls Pothole Rocks this morning.
Gulls sailed high overhead on the wind, taking a speedy ride downriver toward Chesapeake Bay, the Atlantic coast, and countless fast-food restaurant parking lots where surviving winter weather is more of a sure thing. Nearly a thousand Ring-billed Gulls soared past the migration count lookout today. Thirteen Herring Gulls and four Great Black-backed Gulls were among them.
Other migrants today included a Mallard, twenty-nine American Black Ducks, two Bald Eagles, eleven Black Vultures, fifteen Turkey Vultures, five American Goldfinches, and fifteen Red-winged Blackbirds. The wintery weather seems to be prompting these late-season travelers to be on their way.
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You know, today was like many other days at the falls. As I arrive, I have the habit of checking all the power line towers on both river shorelines to see what may be there awaiting discovery. More often than not, something interesting is perched on one or more of the structures…
…sometimes there are large flocks of European Starlings…
…other times there might be one or more Turkey Vultures…
…or possibly a Bald Eagle or two…
…or maybe the fastest-flying bird on the planet…
…or perhaps, wait; what’s he doing up there?
Yes friends, while the birds migrated through high above, down below a coordinated effort was underway to replace some of the electric transmission cable that stretches across the Susquehanna River at Conewago Falls. As you’ll see, this project requires precise planning, preparation, and skill. And it was fascinating to watch!
A helicopter is used to raise/lower men and equipment to/from the top of the towers.
A crew doing preparation work is lifted from a tower on the west shore of Conewago Falls.
A crew member is raised to a tower on the east shore of Conewago Falls to begin the next phase of the project.
Crew members are positioned on the two towers on the west shore.
The helicopter hovers in a stand-by position above the Pothole Rocks. By keeping the chopper downwind from and below the wires being replaced, the pilot avoids putting rotor wash into the work area. Note the linemen on the upper left side of each tower. These men monitored the pulleys as the old cable, followed by the new, was pulled from the west shore to the east.
At the ready, the pilot skillfully hovers his craft, nose into the gusty wind, just 100 feet to the east of the migration count site on the Pothole Rocks.
Even as the chopper maintained position near and immediately over the count lookout, migrating birds continued to be seen streaming in a downriver direction high above.
A migrating immature Bald Eagle passes overhead, apparently undaunted by the commotion created by the use of a helicopter to tend the crew advancing replacement wire across the river below.
With the new cable in place, workers are lifted from the towers and lowered to the ground where they can get out of the cold wind after a job well done.
A very light fog lifted quickly at sunrise. Afterward, there was a minor movement of migrants: forty-nine Ring-billed Gulls, a few Herring Gulls, a Red-shouldered Hawk following the river to the southeast, and small flocks totaling nine Cedar Waxwings and twenty-eight Red-winged Blackbirds.
A Belted Kingfisher in the morning fog.
A Ring-billed Gull calls as active migrants pass overhead on their way downriver.
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In the Riparian Woodland, small mixed flocks of winter resident and year-round resident birds were actively feeding. They must build and maintain a layer of body fat to survive blustery cold nights and the possible lack of access to food during snowstorms. There’s no time to waste; nasty weather could bring fatal hardship to these birds soon.
A Carolina Chickadee (Poecile carolinensis) feeds on the seeds of an Eastern Sycamore (Platanus occidentalis), also known as American Sycamore. Chickadees are generalist feeders, eating invertebrates and suet at feeding stations in addition to the seeds of many plants. Carolina Chickadees are year-round residents at Conewago Falls.
A fast-moving Golden-crowned Kinglet zips from limb to limb to grab tiny insects and other invertebrates. During the winter, these petite birds will carefully probe the bark and crevices of trees to glean enough food to survive. Golden-crowned Kinglets are winter residents at Conewago Falls. In spring, they will depart to nest in coniferous forests.
A Downy Woodpecker (Picoides pubescens) searches an infected tree for insects. They are year-round residents.
Carolina Wrens (Thryothorus ludovicianus) are considered year-round residents at Conewago Falls, though they may withdraw to the south during severe winters. Carolina Wrens sing year-round. Today, their loud melody echoed through the Riparian Woodland all morning.
The tiny bob-tailed Winter Wren is an elusive ground-dwelling winter resident at the falls. You may hear their scolding chatter from rocky areas and tree logs where they climb around mouse-like in search of small invertebrates. Their song is a fast jumble of dainty musical trills that can sometimes be heard echoing through the Riparian Woodland in winter. In spring, they’ll depart to nest in damp coniferous forests.
It was a crisp clear morning with birdless blue skies. The migration has mostly drawn to a close; very little was seen despite a suitable northwest breeze to support a flight. There were no robins and no blackbirds. Not even a starling was seen today. The only highlights were a Bufflehead (Bucephala albeola) and a couple of Swamp Sparrows.
A Swamp Sparrow is coaxed from the dense leafy cover of the Riverine Grasslands of Conewago Falls.
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And now ladies and gentlemen, boys and girls, it’s time for a Thanksgiving Day culinary reminder from the local Conewago Falls Turkey…
“That’s the Conewago Falls Turkey Vulture if you don’t mind. And I’m here to remind you that this Thanksgiving, you don’t have to fight your way in there to get first pickings of the feast. Take it from me, let those flavors and aromas intensify over time. And juices, who needs juices? Let that stuff congeal so everything sticks to your ribs. Are you paying attention? I’m telling you, just back off, let the crowd die down, then get in there and devour those leftovers. They’re the best. You’ll thank me later!”
Temperatures plummeted to well below freezing during the past two nights, but there was little sign of it in Conewago Falls this morning. The fast current in the rapids and swirling waters in flooded Pothole Rocks did not freeze. Ice coated the standing water in potholes only in those rocks lacking a favorable orientation to the sun for collecting solar heat during the day to conduct into the water during the cold nights.
On the shoreline, the cold snap has left its mark. Ice covers the still waters of the wetlands. Frost on exposed vegetation lasted until nearly noontime in shady areas. Insect activity is now grounded and out of sight. The leaves of the trees tumble and fall to cover the evidence of a lively summer.
The nocturnal bird flight is narrowing down to just a few species. White-throated Sparrows, a Swamp Sparrow (Melospiza georgiana), and Song Sparrows are still on the move. Though their numbers are not included in the migration count, hundreds of the latter are along the shoreline and in edge habitat around the falls right now. Song Sparrows are present year-round, migrate at night, and are not seen far from cover in daylight, so migratory movements are difficult to detect. It is certain that many, if not all of the Song Sparrows here today have migrated and arrived here recently. The breeding population from spring and summer has probably moved further south. And many of the birds here now may remain for the winter. Defining the moment of this dynamic, yet discrete, population change and logging it in a count would certainly require different methods.
Song Sparrows are now abundant in the brushy edges of fields and woodlands. They may even break into song on sunny days.
Diurnal migration was foiled today by winds from southerly directions and moderating temperatures. The only highlight was an American Robin flight that extended into the morning for a couple of hours after daybreak and totaled over 800 birds. This flight was peppered with an occasional flock of blackbirds. Then too, there were the villains.
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They’re dastardly, devious, selfish, opportunistic, and abundant. Today, they were the most numerous diurnal migrant. Their numbers made this one of the biggest migration days of the season, but they are not recorded on the count sheet. It’s no landmark day. They excite no one. For the most part, they are not recognized as migrants because of their nearly complete occupation of North America south of the taiga. If people build on it or alter it, these birds will be there. They’re everywhere people are. If the rotten attributes of man were wrapped up into one bird, an “anthropoavian”, this would be it.
Meet the European Starling (Sturnus vulgaris). Introduced into North America in 1890, the species has spread across the entire continent. It nests in cavities in buildings and in trees. Starlings are aggressive, particularly when nesting, and have had detrimental impacts on the populations of native cavity nesting birds, particularly Red-headed Woodpeckers, Purple Martins (Progne subis), and Eastern Bluebirds. They commonly terrorize these and other native species to evict them from their nest sites. European Starlings are one of the earlier of the scores of introduced plants and animals we have come to call invasive species.
Noisy flocks of European Starlings are right at home on man-made structures in city and country.
Today, thousands of European Starlings were on the move, working their way down the river shoreline and raiding berries from the vines and trees of the Riparian Woodlands. My estimate is between three and five thousand migrated through during the morning. But don’t worry, thousands more will be around for the winter.
European Starlings mob a Sharp-shinned Hawk from above, a common behavior.
An Eastern Bluebird feeds on the few berries left untouched by passing European Starlings.
The NOAA National Weather Service radar images from last evening provided an indication that there may be a good fallout of birds at daybreak in the lower Susquehanna valley. The moon was bright, nearly full, and there was a gentle breeze from the north to move the nocturnal migrants along. The conditions were ideal.
Rising from daytime roosts in New York and Pennsylvania, then streaming south in moonlit skies, migrating birds are recorded as echoes on this post-sunset composite NEXRAD loop from last evening. (NOAA/National Weather Service image)
The Riparian Woodlands at Conewago Falls were alive with migrants this morning. American Robins and White-throated Sparrows were joined by new arrivals for the season: Brown Creeper (Certhia americana), Ruby-crowned Kinglets (Regulus calendula), Golden-crowned Kinglets (Regulus satrapa), Dark-eyed Junco (Junco hyemalis), and Yellow-rumped Warbler (Setophaga coronata). These are the perching birds one would expect to have comprised the overnight flight. While the individuals that will remain may not yet be among them, these are the species we will see wintering in the Mid-Atlantic states. No trip to the tropics for these hardy passerines.
American Robins continued migratory flight into the first hour of daylight this morning. Their calls are commonly heard at night as migrating individuals pass overhead.
White-throated Sparrows are nocturnal migrants, and are a familiar find on woodland edges and at suburban feeding stations through the winter.
Dark-eyed Juncos, also nocturnal migrants, are common winter residents in the Lower Susquehanna River Watershed, frequently visiting bird feeders.
Heavy rain earlier this week in the Susquehanna River drainage basin has flooded most of the Pothole Rocks; the rapids of Conewago Falls have returned.
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It was a placid morning on Conewago Falls with blue skies dotted every now and then by a small flock of migrating robins or blackbirds. The jumbled notes of a singing Winter Wren (Troglodytes hiemalis) in the Riparian Woodland softly mixed with the sounds of water spilling over the dam. The season’s first Wood Ducks (Aix sponsa), Blue-winged Teal (Spatula discors), Herring Gull (Larus argentatus), Horned Larks (Eremophila alpestris), and White-throated Sparrows (Zonotrichia albicollis) were seen.
There was a small ruckus when one of the adult Bald Eagles from a local pair spotted an Osprey passing through carrying a fish. This eagle’s effort to steal the Osprey’s catch was soon interrupted when an adult eagle from a second pair that has been lingering in the area joined the pursuit. Two eagles are certainly better than one when it’s time to hustle a skinny little Osprey, don’t you think?
But you see, this just won’t do. It’s a breach of eagle etiquette, don’t you know? Soon both pairs of adult eagles were engaged in a noisy dogfight. It was fussing and cackling and the four eagles going in every direction overhead. Things calmed down after about five minutes, then a staring match commenced on the crest of the dam with the two pairs of eagles, the “home team” and the “visiting team”, perched about 100 feet from each other. Soon the pair which seems to be visiting gave up and moved out of the falls for the remainder of the day. The Osprey, in the meantime, was able to slip away.
In recent weeks, the “home team” pair of Bald Eagles, seen regularly defending territory at Conewago Falls, has been hanging sticks and branched tree limbs on the cross members of the power line tower where they often perch. They seem only to collect and display these would-be nest materials when the “visiting team” pair is perched in the nearby tower just several hundred yards away…an attempt to intimidate by homesteading. It appears that with winter and breeding time approaching, territorial behavior is on the increase.
The second migrating Osprey of the day ran the gauntlet of marauding eagles without incident.
In the afternoon, a fresh breeze from the south sent ripples across the waters among the Pothole Rocks. The updraft on the south face of the diabase ridge on the east shore was like a highway for some migrating hawks, falcons, and vultures. Black Vultures (Coragyps atratus) and Turkey Vultures streamed off to the south headlong into the wind after leaving the ridge and crossing the river. A male and female Northern Harrier (Circus hudsonius), ten Red-tailed Hawks, two Red-shouldered Hawks (Buteo lineatus), six Sharp-shinned Hawks, and two Merlins crossed the river and continued along the diabase ridge on the west shore, accessing a strong updraft along its slope to propel their journey further to the southwest. Four high-flying Bald Eagles migrated through, each following the east river shore downstream and making little use of the ridge except to gain a little altitude while passing by.
(Top and Middle) Turkey Vultures riding the fresh breeze and teetering to-and-fro on up-tilted wings. This wing posture is known as a dihedral. (Bottom) More than 100 migrating Black Vultures climbed high on the afternoon breeze to make an oblique crossing of the river and maintain a southbound course.
Late in the afternoon, the local Bald Eagles were again airborne and cackling up a storm. This time they intercepted an eagle coming down the ridge toward the river and immediately forced the bird to climb if it intended to pass. It turned out to be the best sighting of the day, and these “home team” eagles found it first. It was a Golden Eagle (Aquila chrysaetos) in crisp juvenile plumage. On its first southward voyage, it seemed to linger after climbing high enough for the Bald Eagles to loose concern, then finally selected the ridge route and crossed the river to head off to the southwest.
Ring-billed Gulls began feeding during the afternoon as clouds preceding stormy weather approached.
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